eCFR

Electronic Code of Federal Regulations REST API for accessing the official US Code of Federal Regulations, searching regulations, and retrieving regulatory version history.

eCFR publishes 3 APIs on the APIs.io network: Admin Service API, Search Service API, and Versioner Service API. Tagged areas include Federal Regulations, Government, Legal, Compliance, and Open Data.

The eCFR catalog on APIs.io includes 1 Spectral governance ruleset.

eCFR’s developer surface includes documentation, engineering blog, pricing, code examples, and 21 more developer resources.

🌐 Visit website 📡 Source on GitHub

35.6/100 thin ▼ -5.7 Agent 23/100 agent aware Full breakdown ↓
scored 2026-07-28 · rubric v0.6

AccessFree

3 APIs

Federal RegulationsGovernmentLegalComplianceOpen DataUnited States

Kin Score

Kin Score How this is scored →
scored 2026-07-28 · rubric v0.6

Composite quality — 35.6/100 · thin

Contract Quality 8.1 / 25

Developer Ergonomics 2.2 / 20

Commercial Clarity 7.9 / 20

Operational Transparency 3.4 / 13

Governance 8.3 / 12

Discoverability 6.5 / 10

Agent readiness — 23/100 · agent aware

Machine-Readable Contract 18 / 18

Agentic Access Contract 10 / 10

MCP Server 0 / 12

Machine-Readable Auth 0 / 10

Idempotency 0 / 9

Stable Error Semantics 0 / 8

Request/Response Examples 7 / 7

Rate-Limit Signaling 7 / 7

Typed Event Surface 0 / 6

Agent Skills 0 / 5

Well-Known Catalog 0 / 4

Consent & Bot Identity 0 / 3

A2A Agent Card 0 / 8

Dry-Run / Simulate Mode 0 / 4

Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. This rating is computed from github.com/api-evangelist/ecfr: open an issue to ask a question, or submit a pull request to add artifacts. Want it done for you? Prioritized profiling — $2,500 →

APIs 3

Individual APIs this provider publishes, each with its own machine-readable definition.

eCFR Admin Service API

Access eCFR metadata through JSON

eCFR Search Service API

Historical search of the eCFR

eCFR Versioner Service API

Access CFR content and structure files through JSON and XML

Pricing Plans 1

Published pricing tiers and plan structures.

Ecfr Plans Pricing

1 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

Ecfr Rate Limits

1 limits

RATE LIMITS

FinOps 1

Cost, billing, and metering signals for API financial operations.

Ecfr Finops

FINOPS

Spectral Rules 1

Spectral governance rulesets for linting and validating these APIs.

eCFR API Rules

5 rules · 4 warnings 1 info

SPECTRAL

JSON Schema 7

Standalone JSON Schema definitions for this provider's data models.

AgenciesResponse

1 properties

JSON SCHEMA

Agency

Authentication, domain security, vulnerability disclosure, and trust-center signals.

Ecfr Domain Security

TLSv1.3 · HSTS · DNSSEC · DMARC

SECURITY

Ecfr Vulnerability Disclosure

security.txt · contact published

SECURITY

Agentic Access 1

Recommended x-agentic-access execution contracts for AI agents.

Ecfr Agentic Access

15 operations

15 operations · 0 acting

AGENTIC

Resources

Documentation 8

Reference material describing how the API behaves

Documentation

OpenAPI

JSONSchema

JSONSchema

JSONSchema

JSONSchema

Pricing, plans, and the legal terms of use

Pricing

Pricing

Plans

Plans

FinOps

FinOps

Company 2

The organization behind the API

Website

Website

Blog

Blog

Source (apis.yml)

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.
accessModel:
  pricing: free
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Free
  confidence: medium
  source:
  - plans
  generated: '2026-07-22'
  method: derived
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/ecfr.png
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:ecfr-admin-service-api
  name: eCFR Admin Service API
  description: Access eCFR metadata through JSON
  humanURL: https://www.ecfr.gov/developers/documentation/api/v1
  baseURL: https://www.ecfr.gov/api/versioner/v1
  tags:
  - Admin Service
  properties:
  - type: OpenAPI
    url: openapi/ecfr-admin-service-api-openapi.yml
  - type: Documentation
    url: https://www.ecfr.gov/developers/documentation/api/v1
- aid: ecfr:ecfr-search-service-api
  name: eCFR Search Service API
  description: Historical search of the eCFR
  humanURL: https://www.ecfr.gov/developers/documentation/api/v1
  baseURL: https://www.ecfr.gov/api/versioner/v1
  tags:
  - Search Service
  properties:
  - type: OpenAPI
    url: openapi/ecfr-search-service-api-openapi.yml
  - type: Documentation
    url: https://www.ecfr.gov/developers/documentation/api/v1
- aid: ecfr:ecfr-versioner-service-api
  name: eCFR Versioner Service API
  description: Access CFR content and structure files through JSON and XML
  humanURL: https://www.ecfr.gov/developers/documentation/api/v1
  baseURL: https://www.ecfr.gov/api/versioner/v1
  tags:
  - Versioner Service
  properties:
  - type: OpenAPI
    url: openapi/ecfr-versioner-service-api-openapi.yml
  - type: Documentation
    url: https://www.ecfr.gov/developers/documentation/api/v1
common:
- type: AgenticAccess
  url: agentic-access/ecfr-agentic-access.yml
- type: VulnerabilityDisclosure
  url: security/ecfr-vulnerability-disclosure.yml
- type: DomainSecurity
  url: security/ecfr-domain-security.yml
- 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