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eCFR (Electronic Code of Federal Regulations)

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eCFR — the Electronic Code of Federal Regulations: the CURRENT, codified text of U.S. federal regulations (Office of the Federal Register / NARA). Search what the rules SAY NOW, walk the nested hierarchy (title → chapter → part → section) of any CFR title as of a date, and trace the change/version history of a regulatory part. The companion to the Federal Register: the Federal Register is "what just changed" (the rules/notices feed), eCFR is "what the regulation says today" (the codified text). Energy/O&G/environmental titles: Title 40 = EPA/Environment (incl. Part 98 GHG reporting & methane NSPS), Title 30 = Mineral Resources (MSHA, BSEE/BOEM offshore), Title 18 = FERC, Title 43 = BLM/Public Lands. No auth.

Get this contract as JSON

Provenance

PublishereCFR (Electronic Code of Federal Regulations)
API basehttps://www.ecfr.gov/api

Freshness & coverage

FreshnessFreshness not declared
GeographicNot declared
TemporalNot declared
AuthenticationNo credentials required

Methods (6)

  • searchRegulations

    read

    Full-text search of the current codified CFR by keyword, optionally narrowed by agency

    Input schema
    {
  "type": "object",
  "properties": {
    "query": {
      "type": "string",
      "examples": [
        "methane"
      ]
    },
    "agencySlug": {
      "type": "string",
      "examples": [
        "environmental-protection-agency"
      ],
      "oneOf": [
        {
          "type": "string"
        },
        {
          "type": "array",
          "items": {
            "type": "string"
          }
        }
      ]
    },
    "perPage": {
      "type": "number",
      "examples": [
        20
      ]
    },
    "page": {
      "type": "number"
    }
  },
  "additionalProperties": false
}

    query required; optional agencySlug; perPage 1-100 and page. Returns paged.

  • countSearchResults

    read

    Count-only for a full-text search (no result bodies)

    Input schema
    {
  "type": "object",
  "properties": {
    "query": {
      "type": "string",
      "examples": [
        "methane"
      ]
    },
    "agencySlug": {
      "type": "string",
      "examples": [
        "environmental-protection-agency"
      ],
      "oneOf": [
        {
          "type": "string"
        },
        {
          "type": "array",
          "items": {
            "type": "string"
          }
        }
      ]
    }
  },
  "additionalProperties": false
}

    query required; optional agencySlug. Uses /search/v1/count without a .json.

  • listTitles

    read

    List all 50 CFR titles with their latest issue/amendment dates

    Input schema
    {
  "type": "object",
  "properties": {},
  "additionalProperties": false
}

    No args. Returns title number, name, latest issue date, and currency date.

  • getTitleStructure

    read

    Nested hierarchy (title → chapter → part → section) of a CFR title as of a date

    Input schema
    {
  "type": "object",
  "properties": {
    "title": {
      "type": "number",
      "examples": [
        40
      ]
    },
    "date": {
      "type": "string"
    }
  },
  "additionalProperties": false
}

    title required; date optional. Missing date resolves the title's latest issue.

  • getPartVersionHistory

    read

    Change/version history for a CFR part

    Input schema
    {
  "type": "object",
  "properties": {
    "title": {
      "type": "number",
      "examples": [
        40
      ]
    },
    "part": {
      "type": "string",
      "examples": [
        "98"
      ],
      "oneOf": [
        {
          "type": "string"
        },
        {
          "type": "number"
        }
      ]
    }
  },
  "additionalProperties": false
}

    title and part required. Returns parsed content_versions history.

  • getServiceInfo

    read

    Static API overview — methods, energy-domain CFR title map, agency-slug source, and gotchas

    Input schema
    {
  "type": "object",
  "properties": {},
  "additionalProperties": false
}