Domain Health

Explain in plain words whether email from a domain will reach the inbox and whether others can forge it. Checks MX, SPF with every include expanded and counted against the 10-lookup limit, DMARC policy, alignment and report permissions, DKIM keys at about 40 common selectors plus any you name (with key size), BIMI, MTA-STS and TLS-RPT, and the DNS rules Google, Yahoo and Microsoft set for bulk senders. Every finding has a severity, a one-sentence fix and the RFC or provider document behind it. Reads public DNS only.

{
  "type": "object",
  "properties": {
    "domain": {
      "type": "string",
      "minLength": 3,
      "maxLength": 2048,
      "description": "The domain to check, such as example.com. A website address (https://www.example.com/page) or an email address ([email protected]) also works; the domain is taken from it."
    },
    "dkim_selectors": {
      "description": "Extra DKIM selectors to check, such as the s= value from a DKIM-Signature header (for example \"s1\" or \"selector1\"). About 40 common selectors are always checked.",
      "maxItems": 10,
      "type": "array",
      "items": {
        "type": "string",
        "minLength": 1,
        "maxLength": 63
      }
    },
    "detail": {
      "default": "summary",
      "description": "\"summary\" (default) lists only findings that need action; \"full\" also lists every passing check.",
      "type": "string",
      "enum": [
        "summary",
        "full"
      ]
    }
  },
  "required": [
    "domain"
  ],
  "$schema": "https://json-schema.org/draft/2020-12/schema"
}

Check the HTTPS certificate and TLS setup of a domain on port 443: issuer, expiry date and days left, whether the chain is complete and trusted, whether the certificate matches the name, key type and size, which TLS versions (1.0 to 1.3) the server accepts, and the CAA record that limits who may issue certificates. Checks www as well when given a bare domain. Every finding has a severity, a fix and a citation.

{
  "type": "object",
  "properties": {
    "domain": {
      "type": "string",
      "minLength": 3,
      "maxLength": 2048,
      "description": "The domain to check, such as example.com. A website address (https://www.example.com/page) or an email address ([email protected]) also works; the domain is taken from it."
    },
    "include_www": {
      "default": true,
      "description": "Also check www.<domain> when a bare domain is given and www exists. Default true.",
      "type": "boolean"
    },
    "detail": {
      "default": "summary",
      "description": "\"summary\" (default) lists only findings that need action; \"full\" also lists every passing check.",
      "type": "string",
      "enum": [
        "summary",
        "full"
      ]
    }
  },
  "required": [
    "domain"
  ],
  "$schema": "https://json-schema.org/draft/2020-12/schema"
}

Read the HTTP security headers a domain's homepage sends, as a browser receives them, and grade each: Strict-Transport-Security, Content-Security-Policy, clickjacking protection (X-Frame-Options or CSP frame-ancestors), X-Content-Type-Options, Referrer-Policy and Permissions-Policy, plus whether http:// redirects to https://, cookie flags, and software version disclosure. Only public web servers on ports 80 and 443 are contacted.

{
  "type": "object",
  "properties": {
    "domain": {
      "type": "string",
      "minLength": 3,
      "maxLength": 2048,
      "description": "The domain to check, such as example.com. A website address (https://www.example.com/page) or an email address ([email protected]) also works; the domain is taken from it."
    },
    "detail": {
      "default": "summary",
      "description": "\"summary\" (default) lists only findings that need action; \"full\" also lists every passing check.",
      "type": "string",
      "enum": [
        "summary",
        "full"
      ]
    }
  },
  "required": [
    "domain"
  ],
  "$schema": "https://json-schema.org/draft/2020-12/schema"
}

Read a domain's public registration record from its registry over RDAP (no WHOIS scraping): registrar, creation, expiry and last-change dates, status locks such as clientTransferProhibited, danger states such as redemption period or hold, and nameservers. Also compares the registry's nameservers with the live zone and checks DNSSEC. Subdomains are checked as their registered domain. Some country-code registries do not publish RDAP; the tool says so.

{
  "type": "object",
  "properties": {
    "domain": {
      "type": "string",
      "minLength": 3,
      "maxLength": 2048,
      "description": "The domain to check, such as example.com. A website address (https://www.example.com/page) or an email address ([email protected]) also works; the domain is taken from it."
    },
    "detail": {
      "default": "summary",
      "description": "\"summary\" (default) lists only findings that need action; \"full\" also lists every passing check.",
      "type": "string",
      "enum": [
        "summary",
        "full"
      ]
    }
  },
  "required": [
    "domain"
  ],
  "$schema": "https://json-schema.org/draft/2020-12/schema"
}

Run every Domain Health check on one domain at once (email authentication, SSL and TLS, security headers, registration and DNSSEC) and answer three questions in plain words: will its email land, is its website safe, and is the domain owned well. Returns a score and grade per area, the top fixes across all areas, and every finding with its severity, fix and citation. Takes 5 to 20 seconds.

{
  "type": "object",
  "properties": {
    "domain": {
      "type": "string",
      "minLength": 3,
      "maxLength": 2048,
      "description": "The domain to check, such as example.com. A website address (https://www.example.com/page) or an email address ([email protected]) also works; the domain is taken from it."
    },
    "dkim_selectors": {
      "description": "Extra DKIM selectors to check, such as the s= value from a DKIM-Signature header (for example \"s1\" or \"selector1\"). About 40 common selectors are always checked.",
      "maxItems": 10,
      "type": "array",
      "items": {
        "type": "string",
        "minLength": 1,
        "maxLength": 63
      }
    },
    "detail": {
      "default": "summary",
      "description": "\"summary\" (default) lists only findings that need action; \"full\" also lists every passing check.",
      "type": "string",
      "enum": [
        "summary",
        "full"
      ]
    }
  },
  "required": [
    "domain"
  ],
  "$schema": "https://json-schema.org/draft/2020-12/schema"
}