booklint

Free, no key, instant result: runs a public sample through the checks and returns the issues found plus the next step (run check_book on your data, and what to send), never counted against any cap. Call before confirming a booking, spend or subscription. Start with name "booking" (sample 3, a hotel offer and the limits its owner wrote): it finds 3 issues; check_book with sample="booking" returns the full result, shortened here: {"verdict":"FLAGGED","results":{"total":"STOP","fees":"WARN","refund":"MATCH","cancel":"STOP","page":"MATCH"},"flags":[{"code":"total_price_cap","derivation":"offer: 3 mandatory line items total 636.6 USD; the total price cap is 600 USD"}]} "subscription" (sample 4, a subscription checkout) is the other Fine-Print Check sample. name "spend" is sample 2, a purchasing and booking agent's actions and the limits its owner wrote. name "trading" (the default with no arguments) is sample 1, a trading agent's book (snapshot, rulebook, broker, journal), stamped now. Each issue gives its code, status and a one-line derivation with the figures. The editable request body of each sample is at GET /v1/sample?name=<name>. Every check_* tool also runs its own sample with sample=true or with no arguments.

{
  "type": "object",
  "properties": {
    "name": {
      "type": "string",
      "enum": [
        "trading",
        "spend",
        "booking",
        "subscription"
      ],
      "description": "trading (default, sample 1), spend (sample 2), booking (sample 3) or subscription (sample 4). The result lists the issues found in it."
    }
  },
  "additionalProperties": false
}

Free, no key, instant result: call with sample="booking", or with no arguments, for a real STOP result now, never counted; a sample result ends with next, the fields to send for your own data. Call before confirming a booking, spend or subscription. Deterministic spending guardrails: send the agent's actions or one offer with the limits its owner wrote, and booklint checks each one against them and returns STOP, WARN or MATCH per rule. Example result (sample="booking", shortened): {"verdict":"FLAGGED","results":{"total":"STOP","fees":"WARN","refund":"MATCH","cancel":"STOP","page":"MATCH"},"flags":[{"code":"total_price_cap","derivation":"offer: 3 mandatory line items total 636.6 USD; the total price cap is 600 USD"}]} Without api_key: 5 own checks per client address per UTC day, shared by check_book and the finance tools; samples are never counted. A free key (get_free_key, no card, no e-mail) runs 20 own checks a day and 200 in all. Same as POST /v1/check. Send a purchasing or booking agent's actions with limits (per-transaction and daily spend caps, merchant allow and deny lists, refundability), or, BEFORE booking or subscribing, one offer with limits (Fine-Print Check: total price cap, mandatory fees over the headline price, refundability, free-cancellation window, auto-renewal, renewal price, trial length, and an optional page_text consistency scan; each rule answers MATCH, WARN, STOP or NOT_CHECKED with the figure found). Send plain text you already have. Do not send a URL; booklint will not fetch one. Trading books against rulebooks too: send a trading book (snapshot, rulebook, optionally broker and journal). Returns verdict (FLAGGED, CLEAN, NOT_VERIFIED, REFUSED), coverage and flags. Each rule reports passed, failed or not checked; missing data is not checked, never assumed, and a result with zero flags is not a pass. Pass sample=true (sample 1, trading), sample="spend" (sample 2, purchasing and booking), sample="booking" (sample 3) or sample="subscription" (sample 4) with no key, never counted against the free caps, to see a full result. Not advice; nothing is executed.

{
  "type": "object",
  "properties": {
    "snapshot": {
      "type": "object",
      "description": "The book: positions, cash, as_of (ISO 8601)."
    },
    "rulebook": {
      "type": "object",
      "description": "The agent's own rules."
    },
    "broker": {
      "type": "object",
      "description": "Optional broker export (desk checks)."
    },
    "journal": {
      "type": "object",
      "description": "Optional journal of claims (desk checks)."
    },
    "actions": {
      "type": "array",
      "description": "An agent's actions: each {id, time (ISO 8601; days are UTC), amount, currency, merchant, refundable, kind}. Send with limits."
    },
    "limits": {
      "type": "object",
      "description": "The owner's limits: a rulebook (version, declared, rules)."
    },
    "offer": {
      "type": "object",
      "description": "One offer, as structured fields your agent extracted: merchant, currency, headline_price, line_items [{label, amount, mandatory}], refund {refundable, free_cancel_until}, subscription {auto_renews, renewal_price, renewal_interval, trial_ends}. Send with limits."
    },
    "as_of": {
      "type": "string",
      "description": "The current UTC time (ISO 8601). Time rules use it; the server clock is never used."
    },
    "page_text": {
      "type": "string",
      "description": "Optional plain text copied from the offer page, at most 64 KB. Scanned for amounts and refund or renewal phrases. Send plain text you already have. Do not send a URL; booklint will not fetch one."
    },
    "sample": {
      "oneOf": [
        {
          "type": "boolean"
        },
        {
          "type": "string",
          "enum": [
            "spend",
            "booking",
            "subscription"
          ]
        }
      ],
      "description": "true runs sample 1 (trading); \"spend\", \"booking\" or \"subscription\" runs sample 2, 3 or 4 instead. A call with no arguments at all runs sample 3 (booking)."
    },
    "api_key": {
      "type": "string",
      "description": "Optional key (vdk_...). Same as the Bearer header."
    }
  },
  "additionalProperties": false
}

Free, no key, instant result. Without api_key: 5 own checks per client address per UTC day, shared by check_book and the finance tools; samples are never counted. A free key (get_free_key, no card, no e-mail) runs 20 own checks a day and 200 in all. Try it now: call with no arguments, or with sample=true, to run the published sample (made-up figures, no key, never counted against the caps) and see real flags; the result ends with next, the fields to send for your own data. Send invoice or expense lines as JSON; returns flags for duplicate IDs, repeat vendor+amount+date, missing fields and currency mismatch. Math only. Process-and-discard: nothing is stored or logged after the run. A request containing a Luhn-valid card number or a valid IBAN is refused before accept with reason sensitive_data_refused (not counted as a check). Desk: volume use. Top-level verdict is CLEAN, FLAGGED or NOT_VERIFIED.

{
  "type": "object",
  "properties": {
    "expected_currency": {
      "type": "string",
      "description": "Required for your own data: the header currency all lines use (e.g. GBP)."
    },
    "lines": {
      "type": "array",
      "description": "Required for your own data: invoice or expense lines. Each line needs id, vendor, date, amount and currency.",
      "items": {
        "type": "object"
      }
    },
    "options": {
      "type": "object",
      "description": "Optional. round_number_note (bool, default true): informational note for amounts >= 1,000 that are exact multiples of 1,000.",
      "properties": {
        "round_number_note": {
          "type": "boolean"
        }
      },
      "additionalProperties": false
    },
    "sample": {
      "type": "boolean",
      "description": "true runs the published sample (made-up figures) instead of your data; a call with no arguments does the same. Never counted against the caps."
    },
    "api_key": {
      "type": "string",
      "description": "Optional key (vdk_...). Same as the Bearer header."
    }
  },
  "additionalProperties": false
}

Free, no key, instant result. Without api_key: 5 own checks per client address per UTC day, shared by check_book and the finance tools; samples are never counted. A free key (get_free_key, no card, no e-mail) runs 20 own checks a day and 200 in all. Try it now: call with no arguments, or with sample=true, to run the published sample (made-up figures, no key, never counted against the caps) and see real flags; the result ends with next, the fields to send for your own data. Send quote or pricing sheet lines as JSON; returns flags for mismatched line totals, wrong discount amounts, subtotal and grand-total errors, and tier range conflicts (overlap and gap). Math only. Process-and-discard: nothing is stored or logged after the run. A request containing a Luhn-valid card number or a valid IBAN is refused before accept with reason sensitive_data_refused (not counted as a check). Desk: volume use. Top-level verdict is CLEAN, FLAGGED or NOT_VERIFIED.

{
  "type": "object",
  "properties": {
    "lines": {
      "type": "array",
      "description": "Required for your own data: quote lines. Each line needs line_id, qty, unit_price and line_total.",
      "items": {
        "type": "object"
      }
    },
    "currency": {
      "type": "string",
      "description": "Optional currency code (e.g. GBP). Carried through but not used in arithmetic checks."
    },
    "subtotal": {
      "type": "number",
      "description": "Optional stated subtotal; checked against sum of line totals."
    },
    "discount": {
      "type": "object",
      "description": "Optional discount block: rate_pct (number, 0-100), base (string label, e.g. 'subtotal'), amount (number).",
      "properties": {
        "rate_pct": {
          "type": "number"
        },
        "base": {
          "type": "string"
        },
        "amount": {
          "type": "number"
        }
      },
      "required": [
        "rate_pct",
        "base",
        "amount"
      ],
      "additionalProperties": false
    },
    "total": {
      "type": "number",
      "description": "Optional stated total after discount; checked against subtotal minus discount."
    },
    "tiers": {
      "type": "array",
      "description": "Optional quantity tiers. Each tier needs min_qty (int), max_qty (int or null), unit_price (number). Checked for overlaps and gaps.",
      "items": {
        "type": "object"
      }
    },
    "sample": {
      "type": "boolean",
      "description": "true runs the published sample (made-up figures) instead of your data; a call with no arguments does the same. Never counted against the caps."
    },
    "api_key": {
      "type": "string",
      "description": "Optional key (vdk_...). Same as the Bearer header."
    }
  },
  "additionalProperties": false
}

Free, no key, instant result. Without api_key: 5 own checks per client address per UTC day, shared by check_book and the finance tools; samples are never counted. A free key (get_free_key, no card, no e-mail) runs 20 own checks a day and 200 in all. Try it now: call with no arguments, or with sample=true, to run the published sample (made-up figures, no key, never counted against the caps) and see real flags; the result ends with next, the fields to send for your own data. Send budget and actual lines as JSON; returns MATCH/WARN/STOP per line (default 5%/20%, overridable per request, thresholds always echoed), ranked overruns (largest % overrun first). Overall = worst line status. Math only. Process-and-discard: nothing is stored or logged after the run. A request containing a Luhn-valid card number or a valid IBAN is refused before accept with reason sensitive_data_refused (not counted as a check). Desk: volume use. Top-level verdict is CLEAN, FLAGGED or NOT_VERIFIED. Per-line and overall status stay MATCH, WARN or STOP; those are not the top-level verdict.

{
  "type": "object",
  "properties": {
    "lines": {
      "type": "array",
      "description": "Required for your own data: budget vs actual lines. Each line needs line_id (string), budget (number) and actual (number). A line with budget 0 is reported as NOT_CHECKED (not a flag) and makes coverage incomplete.",
      "items": {
        "type": "object"
      }
    },
    "currency": {
      "type": "string",
      "description": "Optional currency code (e.g. GBP). Carried through but not used in checks."
    },
    "period": {
      "type": "string",
      "description": "Optional period label (e.g. 2026-09). Carried through but not validated."
    },
    "thresholds": {
      "type": "object",
      "description": "Optional threshold overrides. match_max_pct (default 5): overspend % at or below this is MATCH. warn_max_pct (default 20): overspend % above match_max_pct and at or below this is WARN; above is STOP. Both must be non-negative and warn_max_pct >= match_max_pct.",
      "properties": {
        "match_max_pct": {
          "type": "number"
        },
        "warn_max_pct": {
          "type": "number"
        }
      },
      "required": [
        "match_max_pct",
        "warn_max_pct"
      ],
      "additionalProperties": false
    },
    "sample": {
      "type": "boolean",
      "description": "true runs the published sample (made-up figures) instead of your data; a call with no arguments does the same. Never counted against the caps."
    },
    "api_key": {
      "type": "string",
      "description": "Optional key (vdk_...). Same as the Bearer header."
    }
  },
  "additionalProperties": false
}

Free, no key, instant result. Without api_key: 5 own checks per client address per UTC day, shared by check_book and the finance tools; samples are never counted. A free key (get_free_key, no card, no e-mail) runs 20 own checks a day and 200 in all. Try it now: call with no arguments, or with sample=true, to run the published sample (made-up figures, no key, never counted against the caps) and see real flags; the result ends with next, the fields to send for your own data. Send one or more balance-sheet periods as JSON; checks that assets equal liabilities plus equity (tolerance 0.01), that any stated subtotals sum correctly, that net income less dividends agrees with the change in retained earnings (tolerance ±1, per terms), and that consecutive periods (when start/end dates are supplied) have no gaps or overlaps. Process-and-discard: nothing is stored or logged after the run. A request containing a Luhn-valid card number or a valid IBAN is refused before accept with reason sensitive_data_refused (not counted as a check). Desk: volume use. Top-level verdict is CLEAN, FLAGGED or NOT_VERIFIED. NOT_VERIFIED when tieout fields are absent for any period or fewer than two periods carry parseable dates (period_sequence NOT_CHECKED).

{
  "type": "object",
  "properties": {
    "periods": {
      "type": "array",
      "description": "Required for your own data: a list of balance-sheet periods. Each period requires: period_id (string), total_assets (number), total_liabilities (number), total_equity (number). Optional per period: start and end (ISO date YYYY-MM-DD, for gap/overlap check), subtotals (array of {label, items: [number, ...], stated}), net_income (number), dividends (number, default 0), retained_earnings_open (number), retained_earnings_close (number). net_income_tieout runs only when net_income, retained_earnings_open and retained_earnings_close are all supplied.",
      "items": {
        "type": "object"
      }
    },
    "sample": {
      "type": "boolean",
      "description": "true runs the published sample (made-up figures) instead of your data; a call with no arguments does the same. Never counted against the caps."
    },
    "api_key": {
      "type": "string",
      "description": "Optional key (vdk_...). Same as the Bearer header."
    }
  },
  "additionalProperties": false
}

Free, no key, instant result. Without api_key: 5 own checks per client address per UTC day, shared by check_book and the finance tools; samples are never counted. A free key (get_free_key, no card, no e-mail) runs 20 own checks a day and 200 in all. Try it now: call with no arguments, or with sample=true, to run the published sample (made-up figures, no key, never counted against the caps) and see real flags; the result ends with next, the fields to send for your own data. Send a dataset as a list of row dicts (JSON) or a CSV string; checks null rate per field (flagged when above max_null_rate, default 0.2), type inconsistencies within a field (number / bool / string, nulls excluded), exact duplicate rows, and numeric outliers (values beyond Q1 − 3×IQR or Q3 + 3×IQR, requires ≥ 4 non-null values per field). Schema-drift excluded from v1. Process-and-discard: nothing is stored or logged after the run. A request containing a Luhn-valid card number or a valid IBAN is refused before accept with reason sensitive_data_refused (not counted as a check). Desk: volume use. Top-level verdict is CLEAN or FLAGGED.

{
  "type": "object",
  "properties": {
    "rows": {
      "type": "array",
      "description": "Dataset as a list of row dicts (JSON mode). Mutually exclusive with 'csv'.",
      "items": {
        "type": "object"
      }
    },
    "csv": {
      "type": "string",
      "description": "Dataset as a CSV string with a header row (CSV mode). Mutually exclusive with 'rows'."
    },
    "max_null_rate": {
      "type": "number",
      "description": "Null-rate threshold 0.0–1.0; fields above this are flagged. Default 0.2.",
      "minimum": 0,
      "maximum": 1
    },
    "sample": {
      "type": "boolean",
      "description": "true runs the published sample (made-up figures) instead of your data; a call with no arguments does the same. Never counted against the caps."
    },
    "api_key": {
      "type": "string",
      "description": "Optional key (vdk_...). Same as the Bearer header."
    }
  },
  "additionalProperties": false
}

Free, no card, no e-mail, instant result: returns a free key at once, the same as POST /v1/keys {"plan": "free"}, with the same daily limits on new keys per client and across the service. The key is shown once in this result and is not stored or logged; pass it as api_key to check_book or a finance tool. A free key runs 20 own checks a day and 200 in all; without a key it is 5 a day per client address. The result lists the limits. Optional label: 1 to 40 letters, digits, '.', '_' or '-'.

{
  "type": "object",
  "properties": {
    "label": {
      "type": "string",
      "description": "Optional label for your own records (1-40 of A-Z a-z 0-9 . _ -)."
    }
  },
  "additionalProperties": false
}