aid: ecfr
name: eCFR
description: Electronic Code of Federal Regulations REST API for accessing the official US Code of Federal Regulations, searching regulations, and retrieving regulatory version history.
image: https://kinlane-productions.s3.amazonaws.com/apis-json/apis-json-logo.jpg
url: https://raw.githubusercontent.com/api-evangelist/ecfr/refs/heads/main/apis.yml
created: '2026-06-13'
modified: '2026-06-13'
specificationVersion: '0.19'
tags:
  - Federal Regulations
  - Government
  - Legal
  - Compliance
  - Open Data
  - United States
apis:
  - aid: ecfr:versioner
    name: eCFR Versioner API
    description: Provides access to the full text of CFR titles, parts, sections, and appendices at specific dates, as well as version history for regulatory content. Supports XML format responses for hierarchical regulatory structure.
    image: https://kinlane-productions.s3.amazonaws.com/apis-json/apis-json-logo.jpg
    humanURL: https://www.ecfr.gov/developers/documentation/api/v1
    baseURL: https://www.ecfr.gov/api/versioner/v1
    tags:
      - Regulations
      - Version History
      - CFR Titles
    properties:
      - type: Documentation
        url: https://www.ecfr.gov/developers/documentation/api/v1
      - type: OpenAPI
        url: https://raw.githubusercontent.com/api-evangelist/ecfr/refs/heads/main/openapi/ecfr-openapi.json
    contact:
      - FN: eCFR Developer Support
        url: https://www.ecfr.gov/developers
  - aid: ecfr:search
    name: eCFR Search API
    description: Full-text search across all Code of Federal Regulations content, with support for filtering by title, agency, date ranges, and content type. Returns ranked results with hierarchical context and full-text excerpts.
    image: https://kinlane-productions.s3.amazonaws.com/apis-json/apis-json-logo.jpg
    humanURL: https://www.ecfr.gov/developers/documentation/api/v1
    baseURL: https://www.ecfr.gov/api/search/v1
    tags:
      - Search
      - Full-Text Search
      - Regulations
    properties:
      - type: Documentation
        url: https://www.ecfr.gov/developers/documentation/api/v1
      - type: OpenAPI
        url: https://raw.githubusercontent.com/api-evangelist/ecfr/refs/heads/main/openapi/ecfr-openapi.json
    contact:
      - FN: eCFR Developer Support
        url: https://www.ecfr.gov/developers
  - aid: ecfr:admin
    name: eCFR Admin API
    description: Provides metadata about federal agencies and their CFR references, enabling lookup of which titles and chapters correspond to specific agencies.
    image: https://kinlane-productions.s3.amazonaws.com/apis-json/apis-json-logo.jpg
    humanURL: https://www.ecfr.gov/developers/documentation/api/v1
    baseURL: https://www.ecfr.gov/api/admin/v1
    tags:
      - Agencies
      - Metadata
      - Government
    properties:
      - type: Documentation
        url: https://www.ecfr.gov/developers/documentation/api/v1
      - type: OpenAPI
        url: https://raw.githubusercontent.com/api-evangelist/ecfr/refs/heads/main/openapi/ecfr-openapi.json
    contact:
      - FN: eCFR Developer Support
        url: https://www.ecfr.gov/developers
common:
  - type: Website
    url: https://www.ecfr.gov
  - type: Documentation
    url: https://www.ecfr.gov/developers/documentation/api/v1
  - type: GitHubOrg
    url: https://github.com/usgpo
  - type: Blog
    url: https://www.federalregister.gov/blog
  - type: Pricing
    url: https://www.ecfr.gov/developers
  - type: Plans
    url: https://raw.githubusercontent.com/api-evangelist/ecfr/refs/heads/main/plans/ecfr-plans-pricing.yml
  - type: RateLimits
    url: https://raw.githubusercontent.com/api-evangelist/ecfr/refs/heads/main/rate-limits/ecfr-rate-limits.yml
  - type: FinOps
    url: https://raw.githubusercontent.com/api-evangelist/ecfr/refs/heads/main/finops/ecfr-finops.yml
  - type: OpenAPI
    url: https://raw.githubusercontent.com/api-evangelist/ecfr/refs/heads/main/openapi/ecfr-openapi.json
  - type: JSONSchema
    url: https://raw.githubusercontent.com/api-evangelist/ecfr/refs/heads/main/json-schema/agency.json
  - type: JSONSchema
    url: https://raw.githubusercontent.com/api-evangelist/ecfr/refs/heads/main/json-schema/cfr-title.json
  - type: JSONSchema
    url: https://raw.githubusercontent.com/api-evangelist/ecfr/refs/heads/main/json-schema/search-result.json
  - type: JSONSchema
    url: https://raw.githubusercontent.com/api-evangelist/ecfr/refs/heads/main/json-schema/content-version.json
  - type: JSONSchema
    url: https://raw.githubusercontent.com/api-evangelist/ecfr/refs/heads/main/json-schema/correction.json
  - type: JSONSchema
    url: https://raw.githubusercontent.com/api-evangelist/ecfr/refs/heads/main/json-schema/cfr-ancestor.json
  - type: Vocabulary
    url: https://raw.githubusercontent.com/api-evangelist/ecfr/refs/heads/main/vocabulary/ecfr-vocabulary.json
  - type: JSONLDContext
    url: https://raw.githubusercontent.com/api-evangelist/ecfr/refs/heads/main/json-ld/ecfr-context.json
  - type: Examples
    url: https://raw.githubusercontent.com/api-evangelist/ecfr/refs/heads/main/examples/titles-response.json
  - type: Examples
    url: https://raw.githubusercontent.com/api-evangelist/ecfr/refs/heads/main/examples/agencies-response.json
  - type: Examples
    url: https://raw.githubusercontent.com/api-evangelist/ecfr/refs/heads/main/examples/search-results-response.json
  - type: Examples
    url: https://raw.githubusercontent.com/api-evangelist/ecfr/refs/heads/main/examples/ancestry-response.json
  - type: Examples
    url: https://raw.githubusercontent.com/api-evangelist/ecfr/refs/heads/main/examples/versions-response.json
maintainers:
  - FN: Kin Lane
    email: kin@apievangelist.com