crossref-mcp-server

Resolves a DOI to its full Crossref metadata record: title, authors, editors, affiliations, abstract (when deposited), journal or container with the volume, issue, pages, and article number that locate the work in it, ISSNs and ISBNs, publication date, type, license, full-text links, and funder acknowledgements. The author list is paged: authorCount is the full deposited total, offset and limit select the page (25 authors by default), and when authors remain the response carries a nextOffset to pass back as offset — large-collaboration papers deposit thousands. Post-publication updates are relayed as Crossref records them: updatedBy names each correction, retraction, expression of concern, or new version issued against this work, with its notice DOI and whether the publisher or Retraction Watch recorded it, and updateTo names the works this record is itself a notice for. An absent updatedBy does not mean the work was never updated — coverage depends on those deposits. relations lists related identifiers, such as a preprint and its published version, grouped by relation type; only the Crossref-registered DOIs among them resolve through crossref_get_work. Outgoing references are reported as a count in referencesCount; the reference entries themselves come from crossref_get_references. The isReferencedByCount field reports the total incoming citation count from Crossref; the citing works themselves are not available through Crossref — use OpenAlex for citation graphs.

{
  "type": "object",
  "properties": {
    "doi": {
      "type": "string",
      "pattern": "^(?:https?:\\/\\/(?:dx\\.)?doi\\.org\\/|doi:)?10\\.\\d{4,9}\\/\\S+$",
      "description": "DOI in the format \"10.NNNN/suffix\", e.g. \"10.1038/nature12373\". A resolver-wrapped form — \"https://doi.org/10.1038/nature12373\", \"https://dx.doi.org/…\", \"doi:10.1038/nature12373\" — is accepted and unwrapped."
    },
    "offset": {
      "default": 0,
      "description": "Zero-based index of the first author to return. Pass the nextOffset value from the previous response to continue through a long author list. Only the author list is paged; every other field of the record is returned in full on every page.",
      "type": "integer",
      "minimum": 0,
      "maximum": 9007199254740991
    },
    "limit": {
      "default": 25,
      "description": "Maximum number of authors to return in one page (1–500, default 25). Ordinary records fit in a single page; large-collaboration papers in particle physics and genomics deposit thousands.",
      "type": "integer",
      "minimum": 1,
      "maximum": 500
    }
  },
  "required": [
    "doi"
  ],
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "additionalProperties": false
}

{
  "type": "object",
  "properties": {
    "doi": {
      "type": "string",
      "description": "Canonical DOI"
    },
    "title": {
      "description": "Work title",
      "type": "string"
    },
    "subtitle": {
      "description": "Subtitle when present",
      "type": "string"
    },
    "type": {
      "description": "Work type (e.g. journal-article, book-chapter, posted-content)",
      "type": "string"
    },
    "authors": {
      "description": "Page of the author and contributor list, bounded by limit. Omitted when the record deposits no author field at all.",
      "type": "array",
      "items": {
        "type": "object",
        "properties": {
          "given": {
            "description": "Given (first) name",
            "type": "string"
          },
          "family": {
            "description": "Family (last) name",
            "type": "string"
          },
          "name": {
            "description": "Name when no given/family split is available",
            "type": "string"
          },
          "orcid": {
            "description": "ORCID identifier URI",
            "type": "string"
          },
          "affiliation": {
            "description": "Institutional affiliations",
            "type": "array",
            "items": {
              "type": "object",
              "properties": {
                "name": {
                  "description": "Affiliation name as deposited. Absent when the publisher asserted the organization by identifier alone, where ror carries it instead.",
                  "type": "string"
                },
                "ror": {
                  "description": "ROR identifier for the affiliated organization, when the deposit carries one. It is the whole identity of an affiliation deposited without a name.",
                  "type": "string"
                }
              },
              "additionalProperties": false,
              "description": "Affiliation"
            }
          },
          "sequence": {
            "description": "Author order role (first, additional)",
            "type": "string"
          }
        },
        "additionalProperties": false,
        "description": "Author or contributor"
      }
    },
    "authorCount": {
      "description": "Total number of authors in the deposited list, before offset and limit were applied. Omitted alongside authors when the record deposits no author field.",
      "type": "number"
    },
    "offset": {
      "description": "Zero-based index of the first returned author within the deposited list. Omitted alongside authors when the record deposits no author field.",
      "type": "number"
    },
    "editors": {
      "description": "Editors of the work, or of the book or proceedings containing it, in the entry shape authors use. Returned whole — never paged by offset and limit, and never counted in authorCount. Omitted when the record deposits none.",
      "type": "array",
      "items": {
        "type": "object",
        "properties": {
          "given": {
            "description": "Given (first) name",
            "type": "string"
          },
          "family": {
            "description": "Family (last) name",
            "type": "string"
          },
          "name": {
            "description": "Name when no given/family split is available",
            "type": "string"
          },
          "orcid": {
            "description": "ORCID identifier URI",
            "type": "string"
          },
          "affiliation": {
            "description": "Institutional affiliations",
            "type": "array",
            "items": {
              "type": "object",
              "properties": {
                "name": {
                  "description": "Affiliation name as deposited. Absent when the publisher asserted the organization by identifier alone, where ror carries it instead.",
                  "type": "string"
                },
                "ror": {
                  "description": "ROR identifier for the affiliated organization, when the deposit carries one. It is the whole identity of an affiliation deposited without a name.",
                  "type": "string"
                }
              },
              "additionalProperties": false,
              "description": "Affiliation"
            }
          },
          "sequence": {
            "description": "Author order role (first, additional)",
            "type": "string"
          }
        },
        "additionalProperties": false,
        "description": "Author or contributor"
      }
    },
    "updatedBy": {
      "description": "Update notices Crossref records against this work — corrections, errata, retractions, expressions of concern, withdrawals, new versions — in deposited order. Entries are never merged: the same notice DOI can appear once per source, typed differently by each. Omitted when none is recorded, which does not mean the work was never updated: coverage depends on publisher and Retraction Watch deposits.",
      "type": "array",
      "items": {
        "type": "object",
        "properties": {
          "doi": {
            "type": "string",
            "description": "DOI on the other side of the link: the notice, in updatedBy; the updated work, in updateTo. It is this work's own DOI when the update was made to this record in place."
          },
          "type": {
            "type": "string",
            "description": "Crossref update type as deposited: correction, erratum, corrigendum, addendum, retraction, withdrawal, expression_of_concern, new_version, new_edition, or another code"
          },
          "source": {
            "type": "string",
            "description": "Who recorded the link: publisher, or retraction-watch for an entry Crossref carries from the Retraction Watch database"
          },
          "recordId": {
            "description": "Retraction Watch record ID. Present only on retraction-watch entries.",
            "type": "string"
          },
          "updated": {
            "description": "Date the update was issued",
            "type": "object",
            "properties": {
              "year": {
                "description": "Year",
                "type": "number"
              },
              "month": {
                "description": "Month (1–12)",
                "type": "number"
              },
              "day": {
                "description": "Day of month",
                "type": "number"
              }
            },
            "additionalProperties": false
          }
        },
        "required": [
          "doi",
          "type",
          "source"
        ],
        "additionalProperties": false,
        "description": "Update link"
      }
    },
    "updateTo": {
      "description": "Works this record is an update notice for, in the entry shape updatedBy uses and in deposited order. Omitted when the record is not registered as a notice.",
      "type": "array",
      "items": {
        "type": "object",
        "properties": {
          "doi": {
            "type": "string",
            "description": "DOI on the other side of the link: the notice, in updatedBy; the updated work, in updateTo. It is this work's own DOI when the update was made to this record in place."
          },
          "type": {
            "type": "string",
            "description": "Crossref update type as deposited: correction, erratum, corrigendum, addendum, retraction, withdrawal, expression_of_concern, new_version, new_edition, or another code"
          },
          "source": {
            "type": "string",
            "description": "Who recorded the link: publisher, or retraction-watch for an entry Crossref carries from the Retraction Watch database"
          },
          "recordId": {
            "description": "Retraction Watch record ID. Present only on retraction-watch entries.",
            "type": "string"
          },
          "updated": {
            "description": "Date the update was issued",
            "type": "object",
            "properties": {
              "year": {
                "description": "Year",
                "type": "number"
              },
              "month": {
                "description": "Month (1–12)",
                "type": "number"
              },
              "day": {
                "description": "Day of month",
                "type": "number"
              }
            },
            "additionalProperties": false
          }
        },
        "required": [
          "doi",
          "type",
          "source"
        ],
        "additionalProperties": false,
        "description": "Update link"
      }
    },
    "relations": {
      "description": "Related identifiers — preprints and published versions, other versions, reviews, supplements, parts — grouped by relation type, identifier type, and asserting party, groups in Crossref's order and ids in deposited order. Returned whole. Omitted when the record deposits none.",
      "type": "array",
      "items": {
        "type": "object",
        "properties": {
          "type": {
            "type": "string",
            "description": "Relation type as deposited, read from this work toward ids: is-preprint-of, has-preprint, is-version-of, has-version, has-review, is-supplemented-by, references, has-part, and others"
          },
          "idType": {
            "type": "string",
            "description": "Identifier scheme of ids: doi, uri, pmid, arxiv, accession, issn, isbn, or other"
          },
          "assertedBy": {
            "type": "string",
            "description": "Whose deposit asserts the relation: subject (this work's depositor) or object (the related record's depositor, whose assertion Crossref shows here inverted)"
          },
          "ids": {
            "type": "array",
            "items": {
              "type": "string"
            },
            "description": "Related identifiers in deposited order. A DOI resolves through crossref_get_work only when Crossref registered it; one registered with another agency, such as DataCite, returns doi_not_found there."
          }
        },
        "required": [
          "type",
          "idType",
          "assertedBy",
          "ids"
        ],
        "additionalProperties": false,
        "description": "Related identifiers sharing one relation type, identifier type, and asserting party"
      }
    },
    "abstract": {
      "description": "Abstract when deposited by the publisher. Many records lack abstracts. Publishers deposit it as JATS XML, so this is the text of that deposit with markup removed and character references decoded; a link keeps its tag only where its href holds an address the text it wraps does not already carry, and each formula appears once — MathML as the TeX annotation it carries, otherwise written out linearly (x_i, A^{−1}, √(m), (a+b)/c), and TeX deposited beside MathML in whichever notation comes first.",
      "type": "string"
    },
    "isReferencedByCount": {
      "description": "Incoming citation count from Crossref — the count of works citing this DOI",
      "type": "number"
    },
    "referencesCount": {
      "description": "Number of outgoing references (works cited by this paper)",
      "type": "number"
    },
    "containerTitle": {
      "description": "Journal, book, or proceedings name containing this work",
      "type": "string"
    },
    "volume": {
      "description": "Volume of the container the work appears in",
      "type": "string"
    },
    "issue": {
      "description": "Issue of the container the work appears in",
      "type": "string"
    },
    "page": {
      "description": "Page range as deposited, e.g. \"357-362\"",
      "type": "string"
    },
    "articleNumber": {
      "description": "Article number, deposited by journals that number articles instead of paging them",
      "type": "string"
    },
    "issn": {
      "description": "ISSN(s) of the containing journal",
      "type": "array",
      "items": {
        "type": "string"
      }
    },
    "isbn": {
      "description": "ISBN(s) as deposited — for a book chapter, those of the containing book. Omitted when the record deposits none.",
      "type": "array",
      "items": {
        "type": "string"
      }
    },
    "publisher": {
      "description": "Publisher name",
      "type": "string"
    },
    "published": {
      "description": "Publication date — the first of published, published-print, published-online, and issued that names one. A component Crossref records as unknown is omitted, and so is every component below it.",
      "type": "object",
      "properties": {
        "year": {
          "description": "Year",
          "type": "number"
        },
        "month": {
          "description": "Month (1–12)",
          "type": "number"
        },
        "day": {
          "description": "Day of month",
          "type": "number"
        }
      },
      "additionalProperties": false
    },
    "funders": {
      "description": "Funding acknowledgements",
      "type": "array",
      "items": {
        "type": "object",
        "properties": {
          "name": {
            "description": "Funder name as deposited. Absent when the publisher asserted the funder by identifier alone, where ror carries it instead.",
            "type": "string"
          },
          "doi": {
            "description": "Funder DOI — the Crossref Funder Registry entry this assertion resolved to",
            "type": "string"
          },
          "ror": {
            "description": "ROR identifier for the funding organization, when the deposit carries one. It is the whole identity of an assertion deposited without a name.",
            "type": "string"
          },
          "award": {
            "description": "Grant or award numbers",
            "type": "array",
            "items": {
              "type": "string"
            }
          }
        },
        "additionalProperties": false,
        "description": "Funding assertion"
      }
    },
    "licenses": {
      "description": "License terms",
      "type": "array",
      "items": {
        "type": "object",
        "properties": {
          "url": {
            "type": "string",
            "description": "License URL"
          },
          "contentVersion": {
            "description": "Content version (vor, am, tdm, unspecified)",
            "type": "string"
          },
          "delayInDays": {
            "description": "Embargo delay in days from publication date",
            "type": "number"
          }
        },
        "required": [
          "url"
        ],
        "additionalProperties": false,
        "description": "License entry"
      }
    },
    "links": {
      "description": "Registered full-text links",
      "type": "array",
      "items": {
        "type": "object",
        "properties": {
          "url": {
            "type": "string",
            "description": "Full-text URL"
          },
          "contentType": {
            "description": "MIME type of linked content",
            "type": "string"
          },
          "intendedApplication": {
            "description": "Intended use (text-mining, similarity-checking, etc.)",
            "type": "string"
          }
        },
        "required": [
          "url"
        ],
        "additionalProperties": false,
        "description": "Registered full-text link"
      }
    },
    "url": {
      "description": "DOI resolution URL",
      "type": "string"
    },
    "subject": {
      "description": "Subject classification terms",
      "type": "array",
      "items": {
        "type": "string"
      }
    },
    "language": {
      "description": "Language code (ISO 639)",
      "type": "string"
    },
    "nextOffset": {
      "description": "Offset to pass in the next call to retrieve the following page of authors. Absent when this page reaches the end of the author list.",
      "type": "number"
    },
    "truncated": {
      "description": "True when authors remain beyond this page. Absent when the page is the last.",
      "type": "boolean"
    },
    "shown": {
      "description": "Number of authors returned in this page.",
      "type": "number"
    },
    "cap": {
      "description": "The limit that was applied to this page of authors.",
      "type": "number"
    },
    "notice": {
      "description": "When updatedBy is present, the update types Crossref records for this work with the source of each, and where the notice is read. Then which authors this page covers and the offset that reaches the next ones, or an explanation when the requested offset is past the end of the author list. Both share this one string when both apply. Absent when the page holds the whole author list and no update is recorded.",
      "type": "string"
    },
    "error": {
      "description": "Present when the call failed. Absent on success.",
      "type": "object",
      "properties": {
        "code": {
          "type": "integer",
          "minimum": -9007199254740991,
          "maximum": 9007199254740991,
          "description": "JSON-RPC error code for this failure."
        },
        "message": {
          "type": "string",
          "description": "Human-readable description of what went wrong."
        },
        "data": {
          "type": "object",
          "properties": {
            "reason": {
              "type": "string",
              "description": "Machine-readable failure mode. Declared by this tool: `rate_limited`: Crossref answered HTTP 429 and the limit did not clear inside the retry budget. `upstream_unavailable`: Crossref was unreachable, returned a 5xx status, or served an HTML error page instead of JSON. `malformed_response`: Crossref returned HTTP 200 with a body that is not valid JSON. `request_timeout`: Crossref did not respond within CROSSREF_TIMEOUT_MS, or answered HTTP 408/504. `doi_not_found`: Valid DOI format but no Crossref record exists. Other values are possible when a failure originates below the handler.",
              "examples": [
                "rate_limited",
                "upstream_unavailable",
                "malformed_response",
                "request_timeout",
                "doi_not_found"
              ]
            },
            "recovery": {
              "description": "Actionable next step for the caller.",
              "type": "object",
              "properties": {
                "hint": {
                  "type": "string"
                }
              },
              "required": [
                "hint"
              ],
              "additionalProperties": {}
            },
            "retryable": {
              "description": "Whether retrying may succeed.",
              "type": "boolean"
            }
          },
          "additionalProperties": {}
        }
      },
      "required": [
        "code",
        "message"
      ],
      "additionalProperties": {}
    }
  },
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "additionalProperties": false,
  "anyOf": [
    {
      "not": {
        "required": [
          "error"
        ]
      },
      "required": [
        "doi"
      ]
    },
    {
      "required": [
        "error"
      ]
    }
  ]
}

Returns the outgoing reference list for a DOI — the works cited by this paper. Each reference includes the deposited citation string and, where Crossref has resolved it, a DOI you can look up with crossref_get_work. Results are paged: referenceCount is the full deposited total, and when more remain the response carries a nextOffset to pass back as offset. Reference list coverage varies by publisher; many older works and non-participating publishers have no indexed references. Incoming citations — the works that cite this paper — are not available through Crossref; use OpenAlex for that.

{
  "type": "object",
  "properties": {
    "doi": {
      "type": "string",
      "pattern": "^(?:https?:\\/\\/(?:dx\\.)?doi\\.org\\/|doi:)?10\\.\\d{4,9}\\/\\S+$",
      "description": "DOI in the format \"10.NNNN/suffix\", e.g. \"10.1038/nature12373\". A resolver-wrapped form — \"https://doi.org/10.1038/nature12373\", \"https://dx.doi.org/…\", \"doi:10.1038/nature12373\" — is accepted and unwrapped."
    },
    "offset": {
      "default": 0,
      "description": "Zero-based index of the first reference to return. Pass the nextOffset value from the previous response to continue through a long reference list.",
      "type": "integer",
      "minimum": 0,
      "maximum": 9007199254740991
    },
    "limit": {
      "default": 100,
      "description": "Maximum number of references to return in one page (1–500, default 100). Most works fit in a single page; bibliography records can carry tens of thousands.",
      "type": "integer",
      "minimum": 1,
      "maximum": 500
    }
  },
  "required": [
    "doi"
  ],
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "additionalProperties": false
}

{
  "type": "object",
  "properties": {
    "doi": {
      "type": "string",
      "description": "DOI of the citing work"
    },
    "referenceCount": {
      "type": "number",
      "description": "Total number of references in the deposited list"
    },
    "offset": {
      "type": "number",
      "description": "Zero-based index of the first returned reference within the deposited list"
    },
    "references": {
      "type": "array",
      "items": {
        "type": "object",
        "properties": {
          "key": {
            "description": "Reference key as deposited",
            "type": "string"
          },
          "doi": {
            "description": "Resolved DOI for this reference, when available",
            "type": "string"
          },
          "unstructured": {
            "description": "Citation string as deposited by the publisher, with formatting markup and structured-citation tags removed. Angle-bracketed text that is not recognizable as markup — a cited URL, a Miller index, a DOI fragment — is left exactly as deposited, and so is a link whose href holds an address the text it wraps does not already carry.",
            "type": "string"
          },
          "author": {
            "description": "Author field from the reference entry, with inline formatting markup removed",
            "type": "string"
          },
          "year": {
            "description": "Publication year of the referenced work",
            "type": "string"
          },
          "journalTitle": {
            "description": "Journal title of the referenced work, with inline formatting markup removed",
            "type": "string"
          },
          "articleTitle": {
            "description": "Article title of the referenced work, with inline formatting markup removed",
            "type": "string"
          },
          "volume": {
            "description": "Volume",
            "type": "string"
          },
          "firstPage": {
            "description": "First page",
            "type": "string"
          },
          "issn": {
            "description": "ISSN of the referenced journal",
            "type": "string"
          }
        },
        "additionalProperties": false,
        "description": "Reference entry"
      },
      "description": "Page of the outgoing reference list"
    },
    "nextOffset": {
      "description": "Offset to pass in the next call to retrieve the following page. Absent when this page reaches the end of the reference list.",
      "type": "number"
    },
    "truncated": {
      "description": "True when references remain beyond this page. Absent when the page is the last.",
      "type": "boolean"
    },
    "shown": {
      "description": "Number of references returned in this page.",
      "type": "number"
    },
    "cap": {
      "description": "The limit that was applied to this page.",
      "type": "number"
    },
    "notice": {
      "description": "Coverage guidance when no references are indexed, or a range explanation when the requested offset is past the end of the list. Absent on a normal page.",
      "type": "string"
    },
    "error": {
      "description": "Present when the call failed. Absent on success.",
      "type": "object",
      "properties": {
        "code": {
          "type": "integer",
          "minimum": -9007199254740991,
          "maximum": 9007199254740991,
          "description": "JSON-RPC error code for this failure."
        },
        "message": {
          "type": "string",
          "description": "Human-readable description of what went wrong."
        },
        "data": {
          "type": "object",
          "properties": {
            "reason": {
              "type": "string",
              "description": "Machine-readable failure mode. Declared by this tool: `rate_limited`: Crossref answered HTTP 429 and the limit did not clear inside the retry budget. `upstream_unavailable`: Crossref was unreachable, returned a 5xx status, or served an HTML error page instead of JSON. `malformed_response`: Crossref returned HTTP 200 with a body that is not valid JSON. `request_timeout`: Crossref did not respond within CROSSREF_TIMEOUT_MS, or answered HTTP 408/504. `doi_not_found`: Valid DOI format but no Crossref record exists. Other values are possible when a failure originates below the handler.",
              "examples": [
                "rate_limited",
                "upstream_unavailable",
                "malformed_response",
                "request_timeout",
                "doi_not_found"
              ]
            },
            "recovery": {
              "description": "Actionable next step for the caller.",
              "type": "object",
              "properties": {
                "hint": {
                  "type": "string"
                }
              },
              "required": [
                "hint"
              ],
              "additionalProperties": {}
            },
            "retryable": {
              "description": "Whether retrying may succeed.",
              "type": "boolean"
            }
          },
          "additionalProperties": {}
        }
      },
      "required": [
        "code",
        "message"
      ],
      "additionalProperties": {}
    }
  },
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "additionalProperties": false,
  "anyOf": [
    {
      "not": {
        "required": [
          "error"
        ]
      },
      "required": [
        "doi",
        "referenceCount",
        "offset",
        "references"
      ]
    },
    {
      "required": [
        "error"
      ]
    }
  ]
}

Searches the Crossref works index (~155M records) by free text and/or structured filters. The generic query matches loosely across all fields; scope precisely with the field-specific parameters queryTitle, queryAuthor, and queryContainerTitle, or resolve a known citation to its DOI with queryBibliographic — all combine with each other and with query. Use the filter parameter for structured filtering (object with hyphen-separated Crossref keys). Sort options: relevance, score, is-referenced-by-count, published, deposited, indexed. Each work returns at most authorLimit authors (25 by default) with authorCount reporting the full deposited total, since a single page of large-collaboration papers can carry tens of thousands of author entries; crossref_get_work pages the whole author list for any DOI whose list was cut. Offset-based paging is capped at ~10K results; use cursor="*" to start cursor-based deep paging, then pass the nextCursor value from each response to continue. The walk ends on the page where nextCursor is absent — that page also carries a notice saying the list is exhausted. Cursor and offset cannot be combined.

{
  "type": "object",
  "properties": {
    "query": {
      "description": "Free-text search query, e.g. \"CRISPR gene editing\" or \"climate change adaptation\"",
      "type": "string"
    },
    "queryBibliographic": {
      "description": "Whole-citation match to resolve a known reference to its DOI. Combine title, author, year, and container into one string, e.g. \"Watson Crick molecular structure of nucleic acids Nature 1953\".",
      "type": "string"
    },
    "queryTitle": {
      "description": "Match against work titles only, e.g. \"Array programming with NumPy\".",
      "type": "string"
    },
    "queryAuthor": {
      "description": "Match against author names only, e.g. \"Charles R. Harris\".",
      "type": "string"
    },
    "queryContainerTitle": {
      "description": "Match against the container title (journal or book name) only, e.g. \"Nature\".",
      "type": "string"
    },
    "filter": {
      "description": "Structured filter object using Crossref hyphen-separated keys. All values must be strings. Boolean flag keys (has-abstract, has-references, has-full-text) require string values \"true\" or \"false\". Example: {\"type\":\"journal-article\",\"has-abstract\":\"true\",\"from-pub-date\":\"2023-01-01\"}",
      "type": "object",
      "propertyNames": {
        "type": "string"
      },
      "additionalProperties": {
        "type": "string"
      }
    },
    "fields": {
      "description": "Fields to return (reduces payload). Names are case-sensitive, and each fills one output field: DOI → doi, title → title, type → type, author → authors and authorCount, published / published-print / published-online → published, container-title → containerTitle, publisher → publisher, is-referenced-by-count → isReferencedByCount, score → score, abstract → abstract, volume → volume, issue → issue, page → page, article-number → articleNumber, ISSN → issn. A selected field absent from a work means the record does not deposit it. DOI is always returned whether or not it is listed here, so every result stays resolvable by crossref_get_work, which also returns the fields this list does not cover (license, funder, references, and the rest of the record).",
      "type": "array",
      "items": {
        "type": "string",
        "enum": [
          "DOI",
          "title",
          "type",
          "author",
          "published",
          "published-print",
          "published-online",
          "container-title",
          "publisher",
          "is-referenced-by-count",
          "score",
          "abstract",
          "volume",
          "issue",
          "page",
          "article-number",
          "ISSN"
        ],
        "description": "Crossref select name"
      }
    },
    "rows": {
      "default": 20,
      "description": "Number of results to return per page (1–100, default 20)",
      "type": "integer",
      "minimum": 1,
      "maximum": 100
    },
    "authorLimit": {
      "default": 25,
      "description": "Maximum number of authors to return per work (1–500, default 25). Ordinary records fit under the default; large-collaboration papers deposit thousands, and a page of them is large enough to exhaust a client context. Each work reports its full deposited total as authorCount — call crossref_get_work with that work doi to page the authors this cap left out.",
      "type": "integer",
      "minimum": 1,
      "maximum": 500
    },
    "offset": {
      "description": "Zero-based result offset for offset-based paging. Cannot be used with cursor. Capped at ~10K; use cursor for deeper paging.",
      "type": "integer",
      "minimum": 0,
      "maximum": 9007199254740991
    },
    "cursor": {
      "description": "Cursor token for deep paging. Pass \"*\" to start cursor-based paging (required past ~10K results), then pass the nextCursor value from each response until a response omits it, which means the list is exhausted. Cannot be combined with offset, or with a publication-date sort (published, published-print, published-online), which Crossref does not walk by cursor.",
      "type": "string"
    },
    "sort": {
      "description": "Sort field. The publication-date sorts (published, published-print, published-online) work with offset paging only — Crossref refuses them alongside cursor; every other sort works with either.",
      "anyOf": [
        {
          "type": "string",
          "const": ""
        },
        {
          "type": "string",
          "enum": [
            "relevance",
            "score",
            "is-referenced-by-count",
            "published",
            "published-print",
            "published-online",
            "deposited",
            "indexed",
            "created",
            "updated",
            "references-count"
          ],
          "description": "Crossref sort field"
        }
      ]
    },
    "order": {
      "description": "Sort direction (asc or desc)",
      "anyOf": [
        {
          "type": "string",
          "const": ""
        },
        {
          "type": "string",
          "enum": [
            "asc",
            "desc"
          ],
          "description": "Sort direction"
        }
      ]
    }
  },
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "additionalProperties": false
}

{
  "type": "object",
  "properties": {
    "works": {
      "type": "array",
      "items": {
        "type": "object",
        "properties": {
          "doi": {
            "type": "string",
            "description": "Canonical DOI"
          },
          "title": {
            "description": "Work title",
            "type": "string"
          },
          "type": {
            "description": "Work type",
            "type": "string"
          },
          "authors": {
            "description": "Author list for this work, capped at authorLimit. Omitted when the record deposits no author field.",
            "type": "array",
            "items": {
              "type": "object",
              "properties": {
                "given": {
                  "description": "Given name",
                  "type": "string"
                },
                "family": {
                  "description": "Family name",
                  "type": "string"
                },
                "name": {
                  "description": "Name when no given/family split is available",
                  "type": "string"
                }
              },
              "additionalProperties": false,
              "description": "Author"
            }
          },
          "authorCount": {
            "description": "Total number of authors deposited for this work, before the authorLimit cap. Greater than the length of authors when the cap cut the list; pass the doi of this work to crossref_get_work to page the whole list.",
            "type": "number"
          },
          "published": {
            "description": "Publication date — the first of published, published-print, and published-online that names one. A component Crossref records as unknown is omitted, and so is every component below it.",
            "type": "object",
            "properties": {
              "year": {
                "description": "Year",
                "type": "number"
              },
              "month": {
                "description": "Month",
                "type": "number"
              },
              "day": {
                "description": "Day",
                "type": "number"
              }
            },
            "additionalProperties": false
          },
          "containerTitle": {
            "description": "Journal or container name",
            "type": "string"
          },
          "volume": {
            "description": "Volume of the container the work appears in",
            "type": "string"
          },
          "issue": {
            "description": "Issue of the container the work appears in",
            "type": "string"
          },
          "page": {
            "description": "Page range as deposited, e.g. \"357-362\"",
            "type": "string"
          },
          "articleNumber": {
            "description": "Article number, deposited by journals that number articles instead of paging them",
            "type": "string"
          },
          "issn": {
            "description": "ISSN(s) of the containing journal",
            "type": "array",
            "items": {
              "type": "string"
            }
          },
          "publisher": {
            "description": "Publisher name",
            "type": "string"
          },
          "isReferencedByCount": {
            "description": "Incoming citation count",
            "type": "number"
          },
          "score": {
            "description": "Relevance score assigned by Crossref",
            "type": "number"
          },
          "abstract": {
            "description": "Abstract when present in the indexed record — the text of the publisher’s JATS deposit, with markup removed and character references decoded; a link keeps its tag only where its href holds an address the text it wraps does not already carry, and each formula appears once — MathML as the TeX annotation it carries, otherwise written out linearly (x_i, A^{−1}, √(m), (a+b)/c), and TeX deposited beside MathML in whichever notation comes first",
            "type": "string"
          }
        },
        "required": [
          "doi"
        ],
        "additionalProperties": false,
        "description": "Work summary"
      },
      "description": "Matching works. Empty when nothing matched the query, when an offset runs past the end of the results, or on the page that ends a cursor walk — the notice enrichment says which."
    },
    "nextCursor": {
      "description": "Cursor token to pass as cursor on the next call to continue a cursor walk. Present only on a page requested with cursor, and absent once the walk reaches the end of the list.",
      "type": "string"
    },
    "totalResults": {
      "type": "number",
      "description": "Total matching records in Crossref"
    },
    "returned": {
      "type": "number",
      "description": "Number of records returned in this response"
    },
    "truncated": {
      "description": "True when at least one work on this page had its author list cut by authorLimit. Absent when every work on the page carries its full deposited author list.",
      "type": "boolean"
    },
    "cap": {
      "description": "The per-work author cap applied to this page. Absent when no list was cut.",
      "type": "number"
    },
    "notice": {
      "description": "Guidance on an empty page, naming which of its three causes applies: a query nothing matched, an offset past the end of a list that did match, or a cursor walk that has reached the end of the list. On a page carrying records, present when authorLimit cut at least one work list, naming how many and the route to the rest, or when every query term and filter value was supplied blank, so the page lists the whole index unfiltered. A page needing more than one caveat carries them all in this one string.",
      "type": "string"
    },
    "error": {
      "description": "Present when the call failed. Absent on success.",
      "type": "object",
      "properties": {
        "code": {
          "type": "integer",
          "minimum": -9007199254740991,
          "maximum": 9007199254740991,
          "description": "JSON-RPC error code for this failure."
        },
        "message": {
          "type": "string",
          "description": "Human-readable description of what went wrong."
        },
        "data": {
          "type": "object",
          "properties": {
            "reason": {
              "type": "string",
              "description": "Machine-readable failure mode. Declared by this tool: `rate_limited`: Crossref answered HTTP 429 and the limit did not clear inside the retry budget. `upstream_unavailable`: Crossref was unreachable, returned a 5xx status, or served an HTML error page instead of JSON. `malformed_response`: Crossref returned HTTP 200 with a body that is not valid JSON. `request_timeout`: Crossref did not respond within CROSSREF_TIMEOUT_MS, or answered HTTP 408/504. `unknown_filter`: Crossref rejected a filter key it does not recognize (filter-not-available). `sort_cursor_conflict`: A publication-date sort (published, published-print, published-online) was combined with cursor paging, which Crossref refuses. `invalid_cursor`: Crossref did not recognize the cursor token (HTTP 404 cursor-invalid). `invalid_parameter`: Crossref rejected a parameter value (a filter value of the wrong type or form), or answered HTTP 400 with a body that did not parse. `cursor_offset_conflict`: Both cursor and offset were supplied in the same request. `offset_too_large`: The requested offset exceeds the ~10K Crossref limit for offset-based paging. Other values are possible when a failure originates below the handler.",
              "examples": [
                "rate_limited",
                "upstream_unavailable",
                "malformed_response",
                "request_timeout",
                "unknown_filter",
                "sort_cursor_conflict",
                "invalid_cursor",
                "invalid_parameter",
                "cursor_offset_conflict",
                "offset_too_large"
              ]
            },
            "recovery": {
              "description": "Actionable next step for the caller.",
              "type": "object",
              "properties": {
                "hint": {
                  "type": "string"
                }
              },
              "required": [
                "hint"
              ],
              "additionalProperties": {}
            },
            "retryable": {
              "description": "Whether retrying may succeed.",
              "type": "boolean"
            }
          },
          "additionalProperties": {}
        }
      },
      "required": [
        "code",
        "message"
      ],
      "additionalProperties": {}
    }
  },
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "additionalProperties": false,
  "anyOf": [
    {
      "not": {
        "required": [
          "error"
        ]
      },
      "required": [
        "works",
        "totalResults",
        "returned"
      ]
    },
    {
      "required": [
        "error"
      ]
    }
  ]
}

Finds Crossref journal records by ISSN or title query. Provide issn for an exact single-journal lookup, or query for title-based search returning up to rows results. Title-query results page with offset — the nextOffset enrichment carries the value for the following page, up to offset + rows = 100000. Set include_works to true to also return a page of the matched journal's most recent works; that list pages two ways, in two orders. works_offset is the simple one: newest published first, capped ten times lower at works_offset + rows = 10000. works_cursor has no ceiling and reaches the whole works list, newest registered first — ordered by the date each DOI was registered with Crossref, since Crossref does not walk a publication-date sort by cursor: pass works_cursor="*" on the first call, then chain the nextWorksCursor token from each response. The two cannot be combined, and a cursor walk always starts at the most recently registered work — it cannot resume from an offset. Returns journal metadata: title, publisher, ISSN-L, subject areas, and total DOI count.

{
  "type": "object",
  "properties": {
    "query": {
      "description": "Journal title search query, e.g. \"Nature\" or \"Journal of Machine Learning Research\"",
      "type": "string"
    },
    "issn": {
      "description": "ISSN for exact single-journal lookup (print or electronic, with or without hyphen). Example: \"1234-5678\".",
      "anyOf": [
        {
          "type": "string",
          "const": ""
        },
        {
          "type": "string",
          "pattern": "^\\d{4}-?\\d{3}[\\dX]$",
          "description": "ISSN, e.g. \"1234-5678\""
        }
      ]
    },
    "include_works": {
      "default": false,
      "description": "When true, also return a page of the journal's most recent works — newest published first on an offset page, newest registered first on a works_cursor walk. Requires an unambiguous journal — pass issn when a title query matches more than one. A journal with no ISSN registered has no addressable works list; the works lookup is then skipped and the notice enrichment says so.",
      "type": "boolean"
    },
    "rows": {
      "default": 10,
      "description": "Maximum number of journals to return for title queries, or works when include_works is true (1–100, default 10)",
      "type": "integer",
      "minimum": 1,
      "maximum": 100
    },
    "offset": {
      "default": 0,
      "description": "Zero-based offset into the title-query journal list. Pass the nextOffset value from the previous response to continue. Ignored when issn is set, which resolves exactly one record.",
      "type": "integer",
      "minimum": 0,
      "maximum": 9007199254740991
    },
    "works_offset": {
      "default": 0,
      "description": "Zero-based offset into the journal works list when include_works is true. Pass the nextWorksOffset value from the previous response to continue. Capped at works_offset + rows = 10000; use works_cursor to read the whole list. Cannot be combined with works_cursor.",
      "type": "integer",
      "minimum": 0,
      "maximum": 9007199254740991
    },
    "works_cursor": {
      "description": "Cursor token for deep paging of the journal works list when include_works is true. Pass \"*\" to start the walk at the most recently registered work, then pass the nextWorksCursor value from each response. A walk runs by the date each DOI was registered with Crossref, newest first, not by publication date — Crossref does not walk a publication-date sort by cursor. Has no offset ceiling and cannot be combined with works_offset.",
      "type": "string"
    }
  },
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "additionalProperties": false
}

{
  "type": "object",
  "properties": {
    "journals": {
      "type": "array",
      "items": {
        "type": "object",
        "properties": {
          "title": {
            "description": "Journal title",
            "type": "string"
          },
          "issnL": {
            "description": "Linking ISSN (ISSN-L). Absent when the journal has no linking ISSN registered — Crossref reports that as an explicit null rather than an omitted key.",
            "type": "string"
          },
          "issn": {
            "description": "All ISSN variants for this journal",
            "type": "array",
            "items": {
              "type": "string"
            }
          },
          "publisher": {
            "description": "Publisher name",
            "type": "string"
          },
          "subjects": {
            "description": "Subject classifications",
            "type": "array",
            "items": {
              "type": "object",
              "properties": {
                "name": {
                  "type": "string",
                  "description": "Subject area name"
                }
              },
              "required": [
                "name"
              ],
              "additionalProperties": false,
              "description": "Subject"
            }
          },
          "totalDois": {
            "description": "Total registered DOIs in this journal",
            "type": "number"
          }
        },
        "additionalProperties": false,
        "description": "Journal record"
      },
      "description": "Matching journal records"
    },
    "recentWorks": {
      "description": "Page of works from the matched journal, newest first — by publication date on an offset page, by Crossref registration date on a works_cursor page. Requires include_works, and absent even then when the matched journal has no registered ISSN — the works list is addressable by ISSN alone, and the notice enrichment says so.",
      "type": "array",
      "items": {
        "type": "object",
        "properties": {
          "doi": {
            "type": "string",
            "description": "Work DOI"
          },
          "title": {
            "description": "Work title",
            "type": "string"
          },
          "type": {
            "description": "Work type",
            "type": "string"
          },
          "published": {
            "description": "Publication date — the first of published, published-print, and published-online that names one. A component Crossref records as unknown is omitted, and so is every component below it.",
            "type": "object",
            "properties": {
              "year": {
                "description": "Year",
                "type": "number"
              },
              "month": {
                "description": "Month",
                "type": "number"
              }
            },
            "additionalProperties": false
          },
          "isReferencedByCount": {
            "description": "Incoming citation count",
            "type": "number"
          }
        },
        "required": [
          "doi"
        ],
        "additionalProperties": false,
        "description": "Work summary"
      }
    },
    "journalCount": {
      "type": "number",
      "description": "Number of journal records returned in this page"
    },
    "journalsTotal": {
      "type": "number",
      "description": "Total journal records matching the query in Crossref"
    },
    "nextOffset": {
      "description": "Value to pass as offset on the next call for the following page of journals. Absent when this page ends the matches or the next page would breach the 100000-record offset ceiling.",
      "type": "number"
    },
    "worksTotal": {
      "description": "Total works count for the journal, when include_works is true",
      "type": "number"
    },
    "nextWorksOffset": {
      "description": "Value to pass as works_offset on the next call for the following page of works. Absent when this page ends the works list, the next page would breach the 10000-record offset ceiling, or the page was requested with works_cursor.",
      "type": "number"
    },
    "nextWorksCursor": {
      "description": "Value to pass as works_cursor on the next call for the following page of works. Present only on a page requested with works_cursor, and absent once the walk reaches the end of the works list.",
      "type": "string"
    },
    "notice": {
      "description": "Guidance on a page that needs a caveat: a query nothing matched, an offset or works_offset past the end of a list that did match, a page that stops at one of the route offset ceilings with records still unretrieved, an include_works request that was skipped because the matched journal has no registered ISSN to address its works list by, or a query or issn supplied blank with nothing else to search by, so the page lists every journal unfiltered. Absent otherwise. A page needing more than one caveat carries them all in this one string.",
      "type": "string"
    },
    "error": {
      "description": "Present when the call failed. Absent on success.",
      "type": "object",
      "properties": {
        "code": {
          "type": "integer",
          "minimum": -9007199254740991,
          "maximum": 9007199254740991,
          "description": "JSON-RPC error code for this failure."
        },
        "message": {
          "type": "string",
          "description": "Human-readable description of what went wrong."
        },
        "data": {
          "type": "object",
          "properties": {
            "reason": {
              "type": "string",
              "description": "Machine-readable failure mode. Declared by this tool: `rate_limited`: Crossref answered HTTP 429 and the limit did not clear inside the retry budget. `upstream_unavailable`: Crossref was unreachable, returned a 5xx status, or served an HTML error page instead of JSON. `malformed_response`: Crossref returned HTTP 200 with a body that is not valid JSON. `request_timeout`: Crossref did not respond within CROSSREF_TIMEOUT_MS, or answered HTTP 408/504. `invalid_cursor`: Crossref did not recognize the cursor token (HTTP 404 cursor-invalid). `invalid_parameter`: Crossref rejected a parameter value (a filter value of the wrong type or form), or answered HTTP 400 with a body that did not parse. `issn_not_found`: ISSN lookup returned 404 — ISSN is not registered in Crossref. `ambiguous_journal`: include_works is true but the title query matched more than one journal, making the target ambiguous. `offset_too_large`: offset + rows exceeds the 100000-record ceiling Crossref allows on journal title search. `works_offset_too_large`: works_offset + rows exceeds the 10000-record ceiling Crossref allows on a journal works list. `works_cursor_offset_conflict`: include_works is true and works_cursor was supplied alongside a works_offset above zero. Other values are possible when a failure originates below the handler.",
              "examples": [
                "rate_limited",
                "upstream_unavailable",
                "malformed_response",
                "request_timeout",
                "invalid_cursor",
                "invalid_parameter",
                "issn_not_found",
                "ambiguous_journal",
                "offset_too_large",
                "works_offset_too_large",
                "works_cursor_offset_conflict"
              ]
            },
            "recovery": {
              "description": "Actionable next step for the caller.",
              "type": "object",
              "properties": {
                "hint": {
                  "type": "string"
                }
              },
              "required": [
                "hint"
              ],
              "additionalProperties": {}
            },
            "retryable": {
              "description": "Whether retrying may succeed.",
              "type": "boolean"
            }
          },
          "additionalProperties": {}
        }
      },
      "required": [
        "code",
        "message"
      ],
      "additionalProperties": {}
    }
  },
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "additionalProperties": false,
  "anyOf": [
    {
      "not": {
        "required": [
          "error"
        ]
      },
      "required": [
        "journals",
        "journalCount",
        "journalsTotal"
      ]
    },
    {
      "required": [
        "error"
      ]
    }
  ]
}

Finds funders registered in the Crossref Funder Registry by name or funder DOI. Provide funder_doi for an exact single-funder lookup — the full DOI ("10.13039/100000001"), the bare registry ID ("100000001"), or either behind a doi: or https://doi.org/ prefix — or query for name-based search. Name-query results page with offset — the nextOffset enrichment carries the value for the following page, up to offset + rows = 100000. Set include_works to true to also return a page of the most recent works funded by the matched funder; that list pages two ways, in two orders. works_offset is the simple one: newest published first, capped ten times lower at works_offset + rows = 10000. works_cursor has no ceiling and reaches the whole funded-works list, newest registered first — ordered by the date each DOI was registered with Crossref, since Crossref does not walk a publication-date sort by cursor: pass works_cursor="*" on the first call, then chain the nextWorksCursor token from each response. The two cannot be combined, and a cursor walk always starts at the most recently registered work — it cannot resume from an offset. This list also counts works funded by the funder's registry descendants, which a crossref_search_works filter on {"funder": "10.13039/<id>"} does not. Returns funder name, registry ID, country, and alternate names. The Funder Registry supersedes entries, and a deprecated one answers to the same names as its successor while carrying only a fraction of its works: such a record carries replacedBy with the superseding registry ID and the response carries a notice naming it. The replacement is never followed automatically — re-run with funder_doi set to that ID to get the current entry.

{
  "type": "object",
  "properties": {
    "query": {
      "description": "Funder name search query, e.g. \"National Science Foundation\" or \"Wellcome Trust\"",
      "type": "string"
    },
    "funder_doi": {
      "description": "Funder DOI for exact lookup — the full DOI \"10.13039/100000001\" (NSF) or the bare registry ID \"100000001\". Supersedes query when provided.",
      "anyOf": [
        {
          "type": "string",
          "const": ""
        },
        {
          "type": "string",
          "pattern": "^(?:(?:https?:\\/\\/(?:dx\\.)?doi\\.org\\/|doi:)?10\\.13039\\/)?\\d+$",
          "description": "Funder registry ID or funder DOI, e.g. \"100000001\""
        }
      ]
    },
    "include_works": {
      "default": false,
      "description": "When true, also return a page of works funded by the matched funder. Requires an unambiguous funder — pass funder_doi when a name query matches more than one.",
      "type": "boolean"
    },
    "rows": {
      "default": 10,
      "description": "Maximum funders to return for name queries, or works when include_works is true (1–100, default 10)",
      "type": "integer",
      "minimum": 1,
      "maximum": 100
    },
    "offset": {
      "default": 0,
      "description": "Zero-based offset into the name-query funder list. Pass the nextOffset value from the previous response to continue. Ignored when funder_doi is set, which resolves exactly one record.",
      "type": "integer",
      "minimum": 0,
      "maximum": 9007199254740991
    },
    "works_offset": {
      "default": 0,
      "description": "Zero-based offset into the funded-works list when include_works is true. Pass the nextWorksOffset value from the previous response to continue. Capped at works_offset + rows = 10000; use works_cursor to read the whole list. Cannot be combined with works_cursor.",
      "type": "integer",
      "minimum": 0,
      "maximum": 9007199254740991
    },
    "works_cursor": {
      "description": "Cursor token for deep paging of the funded-works list when include_works is true. Pass \"*\" to start the walk at the most recently registered work, then pass the nextWorksCursor value from each response. A walk runs by the date each DOI was registered with Crossref, newest first, not by publication date — Crossref does not walk a publication-date sort by cursor. Has no offset ceiling and cannot be combined with works_offset.",
      "type": "string"
    }
  },
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "additionalProperties": false
}

{
  "type": "object",
  "properties": {
    "funders": {
      "type": "array",
      "items": {
        "type": "object",
        "properties": {
          "id": {
            "description": "Funder registry ID",
            "type": "string"
          },
          "name": {
            "description": "Funder canonical name",
            "type": "string"
          },
          "altNames": {
            "description": "Alternate names for this funder",
            "type": "array",
            "items": {
              "type": "string"
            }
          },
          "country": {
            "description": "Free-text place the registry records for this funder. Usually a country name, but supranational entries carry values like \"European Union\" — there is no machine-readable country code on the record.",
            "type": "string"
          },
          "uri": {
            "description": "Funder registry URI",
            "type": "string"
          },
          "worksCount": {
            "description": "Number of works associated with this funder in Crossref",
            "type": "number"
          },
          "replacedBy": {
            "description": "Registry IDs that supersede this funder. Present only on a deprecated entry — a deprecated funder carries a fraction of its successor's works, so re-run with funder_doi set to one of these IDs to reach the current entry. Pass a bare ID (\"501100004543\") or the full DOI.",
            "type": "array",
            "items": {
              "type": "string"
            }
          },
          "replaces": {
            "description": "Registry IDs this funder supersedes. Present only when the funder has absorbed a deprecated entry; works registered against those IDs are not counted here.",
            "type": "array",
            "items": {
              "type": "string"
            }
          }
        },
        "additionalProperties": false,
        "description": "Funder record"
      },
      "description": "Matching funder records"
    },
    "fundedWorks": {
      "description": "Page of works funded by the matched funder, newest first — by publication date on an offset page, by Crossref registration date on a works_cursor page. Only present when include_works is true.",
      "type": "array",
      "items": {
        "type": "object",
        "properties": {
          "doi": {
            "type": "string",
            "description": "Work DOI"
          },
          "title": {
            "description": "Work title",
            "type": "string"
          },
          "type": {
            "description": "Work type",
            "type": "string"
          },
          "published": {
            "description": "Publication date — the first of published, published-print, and published-online that names one. A component Crossref records as unknown is omitted, and so is every component below it.",
            "type": "object",
            "properties": {
              "year": {
                "description": "Year",
                "type": "number"
              },
              "month": {
                "description": "Month",
                "type": "number"
              }
            },
            "additionalProperties": false
          },
          "isReferencedByCount": {
            "description": "Incoming citation count",
            "type": "number"
          }
        },
        "required": [
          "doi"
        ],
        "additionalProperties": false,
        "description": "Work summary"
      }
    },
    "funderCount": {
      "type": "number",
      "description": "Number of funder records returned in this page"
    },
    "fundersTotal": {
      "type": "number",
      "description": "Total funder records matching the query in Crossref"
    },
    "nextOffset": {
      "description": "Value to pass as offset on the next call for the following page of funders. Absent when this page ends the matches or the next page would breach the 100000-record offset ceiling.",
      "type": "number"
    },
    "fundedWorksTotal": {
      "description": "Total count of funded works for the matched funder, when include_works is true",
      "type": "number"
    },
    "nextWorksOffset": {
      "description": "Value to pass as works_offset on the next call for the following page of funded works. Absent when this page ends the works list, the next page would breach the 10000-record offset ceiling, or the page was requested with works_cursor.",
      "type": "number"
    },
    "nextWorksCursor": {
      "description": "Value to pass as works_cursor on the next call for the following page of funded works. Present only on a page requested with works_cursor, and absent once the walk reaches the end of the works list.",
      "type": "string"
    },
    "notice": {
      "description": "Guidance on a page that needs a caveat: a query nothing matched, an offset or works_offset past the end of a list that did match, a page that stops at one of the route offset ceilings with records still unretrieved, a returned funder that the Funder Registry has deprecated in favor of another entry, or a query or funder_doi supplied blank with nothing else to search by, so the page lists every funder unfiltered. Absent otherwise. A page needing more than one caveat carries them all in this one string.",
      "type": "string"
    },
    "error": {
      "description": "Present when the call failed. Absent on success.",
      "type": "object",
      "properties": {
        "code": {
          "type": "integer",
          "minimum": -9007199254740991,
          "maximum": 9007199254740991,
          "description": "JSON-RPC error code for this failure."
        },
        "message": {
          "type": "string",
          "description": "Human-readable description of what went wrong."
        },
        "data": {
          "type": "object",
          "properties": {
            "reason": {
              "type": "string",
              "description": "Machine-readable failure mode. Declared by this tool: `rate_limited`: Crossref answered HTTP 429 and the limit did not clear inside the retry budget. `upstream_unavailable`: Crossref was unreachable, returned a 5xx status, or served an HTML error page instead of JSON. `malformed_response`: Crossref returned HTTP 200 with a body that is not valid JSON. `request_timeout`: Crossref did not respond within CROSSREF_TIMEOUT_MS, or answered HTTP 408/504. `invalid_cursor`: Crossref did not recognize the cursor token (HTTP 404 cursor-invalid). `invalid_parameter`: Crossref rejected a parameter value (a filter value of the wrong type or form), or answered HTTP 400 with a body that did not parse. `funder_not_found`: Funder DOI lookup returned 404 — funder is not in the Crossref Funder Registry. `ambiguous_funder`: include_works is true but the name query matched more than one funder, making the target ambiguous. `offset_too_large`: offset + rows exceeds the 100000-record ceiling Crossref allows on funder name search. `works_offset_too_large`: works_offset + rows exceeds the 10000-record ceiling Crossref allows on a funded-works list. `works_cursor_offset_conflict`: include_works is true and works_cursor was supplied alongside a works_offset above zero. Other values are possible when a failure originates below the handler.",
              "examples": [
                "rate_limited",
                "upstream_unavailable",
                "malformed_response",
                "request_timeout",
                "invalid_cursor",
                "invalid_parameter",
                "funder_not_found",
                "ambiguous_funder",
                "offset_too_large",
                "works_offset_too_large",
                "works_cursor_offset_conflict"
              ]
            },
            "recovery": {
              "description": "Actionable next step for the caller.",
              "type": "object",
              "properties": {
                "hint": {
                  "type": "string"
                }
              },
              "required": [
                "hint"
              ],
              "additionalProperties": {}
            },
            "retryable": {
              "description": "Whether retrying may succeed.",
              "type": "boolean"
            }
          },
          "additionalProperties": {}
        }
      },
      "required": [
        "code",
        "message"
      ],
      "additionalProperties": {}
    }
  },
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "additionalProperties": false,
  "anyOf": [
    {
      "not": {
        "required": [
          "error"
        ]
      },
      "required": [
        "funders",
        "funderCount",
        "fundersTotal"
      ]
    },
    {
      "required": [
        "error"
      ]
    }
  ]
}

Resolves a Crossref member ID to its publisher/organization record: primary name, alternate imprint names, owned DOI prefixes, registered DOI counts, a per-work-type breakdown, and per-category metadata deposit coverage. Members are the organizations that register DOIs with Crossref, so this answers "what does this publisher publish, and how completely do they deposit metadata?" Resolve a DOI prefix (e.g. "10.1038") to its member ID with crossref_get_prefix, then pass that ID here.

{
  "type": "object",
  "properties": {
    "member_id": {
      "type": "integer",
      "exclusiveMinimum": 0,
      "maximum": 9007199254740991,
      "description": "Crossref member ID — a positive integer, e.g. 297 (Springer) or 340 (PLOS). Resolve a DOI prefix to a member ID first with crossref_get_prefix."
    }
  },
  "required": [
    "member_id"
  ],
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "additionalProperties": false
}

{
  "type": "object",
  "properties": {
    "id": {
      "type": "number",
      "description": "Crossref member ID"
    },
    "primaryName": {
      "description": "Primary publisher/organization name",
      "type": "string"
    },
    "names": {
      "description": "Alternate and imprint names registered under this member",
      "type": "array",
      "items": {
        "type": "string"
      }
    },
    "location": {
      "description": "Publisher location (city, region, country)",
      "type": "string"
    },
    "prefixes": {
      "description": "DOI prefixes owned by this member, e.g. \"10.1038\"",
      "type": "array",
      "items": {
        "type": "string"
      }
    },
    "counts": {
      "type": "object",
      "properties": {
        "totalDois": {
          "description": "Total DOIs registered by this member (current + backfile)",
          "type": "number"
        },
        "currentDois": {
          "description": "DOIs registered in the current (recent) window",
          "type": "number"
        },
        "backfileDois": {
          "description": "DOIs registered in the backfile (older) window",
          "type": "number"
        }
      },
      "additionalProperties": false,
      "description": "Registered DOI counts"
    },
    "worksByType": {
      "description": "DOI counts broken down by work type (all DOIs), sorted by count descending",
      "type": "array",
      "items": {
        "type": "object",
        "properties": {
          "type": {
            "type": "string",
            "description": "Crossref work type, e.g. \"journal-article\", \"book-chapter\", \"posted-content\""
          },
          "count": {
            "type": "number",
            "description": "Number of DOIs of this type registered by the member"
          }
        },
        "required": [
          "type",
          "count"
        ],
        "additionalProperties": false,
        "description": "DOI count for one work type"
      }
    },
    "coverage": {
      "description": "Per-category metadata deposit coverage — each a 0–1 fraction split into current (recent) and backfile (older) DOIs. Signals how completely this publisher deposits references, abstracts, ORCIDs, funders, licenses, and similar metadata.",
      "type": "array",
      "items": {
        "type": "object",
        "properties": {
          "category": {
            "type": "string",
            "description": "Metadata deposit category, e.g. \"references\", \"abstracts\", \"orcids\", \"funders\", \"licenses\", \"affiliations\""
          },
          "current": {
            "description": "Coverage fraction (0–1) among current (recent) DOIs",
            "type": "number"
          },
          "backfile": {
            "description": "Coverage fraction (0–1) among backfile (older) DOIs",
            "type": "number"
          }
        },
        "required": [
          "category"
        ],
        "additionalProperties": false,
        "description": "Metadata deposit coverage for one category"
      }
    },
    "deposits": {
      "description": "Whether the member deposits any metadata with Crossref",
      "type": "boolean"
    },
    "depositsArticles": {
      "description": "Whether the member deposits journal-article metadata",
      "type": "boolean"
    },
    "error": {
      "description": "Present when the call failed. Absent on success.",
      "type": "object",
      "properties": {
        "code": {
          "type": "integer",
          "minimum": -9007199254740991,
          "maximum": 9007199254740991,
          "description": "JSON-RPC error code for this failure."
        },
        "message": {
          "type": "string",
          "description": "Human-readable description of what went wrong."
        },
        "data": {
          "type": "object",
          "properties": {
            "reason": {
              "type": "string",
              "description": "Machine-readable failure mode. Declared by this tool: `rate_limited`: Crossref answered HTTP 429 and the limit did not clear inside the retry budget. `upstream_unavailable`: Crossref was unreachable, returned a 5xx status, or served an HTML error page instead of JSON. `malformed_response`: Crossref returned HTTP 200 with a body that is not valid JSON. `request_timeout`: Crossref did not respond within CROSSREF_TIMEOUT_MS, or answered HTTP 408/504. `member_not_found`: No Crossref member exists for the given ID. Other values are possible when a failure originates below the handler.",
              "examples": [
                "rate_limited",
                "upstream_unavailable",
                "malformed_response",
                "request_timeout",
                "member_not_found"
              ]
            },
            "recovery": {
              "description": "Actionable next step for the caller.",
              "type": "object",
              "properties": {
                "hint": {
                  "type": "string"
                }
              },
              "required": [
                "hint"
              ],
              "additionalProperties": {}
            },
            "retryable": {
              "description": "Whether retrying may succeed.",
              "type": "boolean"
            }
          },
          "additionalProperties": {}
        }
      },
      "required": [
        "code",
        "message"
      ],
      "additionalProperties": {}
    }
  },
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "additionalProperties": false,
  "anyOf": [
    {
      "not": {
        "required": [
          "error"
        ]
      },
      "required": [
        "id"
      ]
    },
    {
      "required": [
        "error"
      ]
    }
  ]
}

Resolves a DOI prefix — the registrant portion of a DOI, e.g. "10.1038" — to its owning Crossref member: the publisher name and numeric member ID. Answers "who publishes DOIs starting with 10.1038?" The Crossref prefix record carries only these three facts (no counts, coverage, or flags); the returned memberId chains directly into crossref_get_member for the full publisher record.

{
  "type": "object",
  "properties": {
    "prefix": {
      "type": "string",
      "pattern": "^10\\.\\d+$",
      "description": "DOI prefix in the format \"10.NNNN\" — the registrant portion of a DOI with no \"/suffix\", e.g. \"10.1038\" or \"10.1371\"."
    }
  },
  "required": [
    "prefix"
  ],
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "additionalProperties": false
}

{
  "type": "object",
  "properties": {
    "prefix": {
      "type": "string",
      "description": "The DOI prefix that was resolved, e.g. \"10.1038\""
    },
    "ownerName": {
      "description": "Name of the member (publisher) that owns this prefix",
      "type": "string"
    },
    "memberId": {
      "description": "Numeric Crossref member ID that owns this prefix — pass to crossref_get_member for the full publisher record",
      "type": "number"
    },
    "error": {
      "description": "Present when the call failed. Absent on success.",
      "type": "object",
      "properties": {
        "code": {
          "type": "integer",
          "minimum": -9007199254740991,
          "maximum": 9007199254740991,
          "description": "JSON-RPC error code for this failure."
        },
        "message": {
          "type": "string",
          "description": "Human-readable description of what went wrong."
        },
        "data": {
          "type": "object",
          "properties": {
            "reason": {
              "type": "string",
              "description": "Machine-readable failure mode. Declared by this tool: `rate_limited`: Crossref answered HTTP 429 and the limit did not clear inside the retry budget. `upstream_unavailable`: Crossref was unreachable, returned a 5xx status, or served an HTML error page instead of JSON. `malformed_response`: Crossref returned HTTP 200 with a body that is not valid JSON. `request_timeout`: Crossref did not respond within CROSSREF_TIMEOUT_MS, or answered HTTP 408/504. `prefix_not_found`: The DOI prefix is not registered with Crossref. Other values are possible when a failure originates below the handler.",
              "examples": [
                "rate_limited",
                "upstream_unavailable",
                "malformed_response",
                "request_timeout",
                "prefix_not_found"
              ]
            },
            "recovery": {
              "description": "Actionable next step for the caller.",
              "type": "object",
              "properties": {
                "hint": {
                  "type": "string"
                }
              },
              "required": [
                "hint"
              ],
              "additionalProperties": {}
            },
            "retryable": {
              "description": "Whether retrying may succeed.",
              "type": "boolean"
            }
          },
          "additionalProperties": {}
        }
      },
      "required": [
        "code",
        "message"
      ],
      "additionalProperties": {}
    }
  },
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "additionalProperties": false,
  "anyOf": [
    {
      "not": {
        "required": [
          "error"
        ]
      },
      "required": [
        "prefix"
      ]
    },
    {
      "required": [
        "error"
      ]
    }
  ]
}