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 22 more developer resources.

🌐 Visit website 📡 Source on GitHub

31.0/100 thin ▬ flat Agent 22/100 agent aware saas Full breakdown ↓
scored 2026-09-08 · rubric v0.20.0

AccessFree

1 APIs

Federal RegulationsGovernment Legal Compliance Open Data United States

Kin Score

Kin Score How this is scored →
scored 2026-09-08 · rubric v0.20.0

Composite quality — 31.0/100 · thin

Contract Quality 9.7 / 21

Developer Ergonomics 0.0 / 17

Access Clarity 4.9 / 17

Operational Transparency 2.9 / 11

Contract Governance 2.6 / 10

Discoverability 5.0 / 9

Regulatory Posture 4.7 / 15

Agent readiness — 22/100 · agent aware

Machine-Readable Contract 18 / 18

Agentic Access Contract 10 / 10

Documented Reversibility 6 / 6

MCP Server 0 / 12

Machine-Readable Auth 0 / 10

Idempotency 9 / 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 4 / 4

Delegated User Identity 0 / 6

Protected Resource Metadata 0 / 5

Registration Without a Human 0 / 6

Agentic Commerce Well-Known Document 0 / 5

Regulatory Posture applies to this provider. Its tags matched the Government & Public Sector regime, so Regulatory Posture carries 15 points of the composite. If this regime is wrong for your business, say so on your provider repo — the applicability map is public and we will correct it.

Create-or-Update Ergonomics does not apply to this provider. The published contracts declare no write operations, and a read-only API cannot create-or-update. The facet is excluded from this provider's denominator entirely — not scored zero. A reference or data API is not deficient for being unable to upsert.

The six quality facets above are damped to 85 points between them, because the conditional facet above carries the other 15. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 85% of its nominal weight, not 100%. The full arithmetic is at apis.io/rating/.

Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. Every facet and dimension name above is a link: it opens that measurement's own page — what it means, the exact checks that feed it, how the whole catalog distributes on it, and the providers at the top of it. 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. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

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

Open Collections 4

Open, tool-agnostic API collections (OpenAPI-derived and Bruno).

API Collection

OPEN COLLECTION

eCFR API Documentation Admin Service API

OPEN COLLECTION

eCFR API Documentation Admin Service Search Service API

OPEN COLLECTION

eCFR API Documentation Admin Service Versioner Service API

OPEN COLLECTION

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

7 properties

JSON SCHEMA

CfrAncestor

6 properties

JSON SCHEMA

CfrTitle

6 properties

JSON SCHEMA

ContentVersion

10 properties

JSON SCHEMA

EcfrCorrection

13 properties

JSON SCHEMA

SearchResult

12 properties

JSON SCHEMA

Scroll for all 7

Examples 5

Example request and response payloads for these APIs.

Agencies Response

1 fields

EXAMPLE

Ancestry Response

1 fields

EXAMPLE

Search Results Response

2 fields

EXAMPLE

Titles Response

2 fields

EXAMPLE

Versions Response

2 fields

EXAMPLE

Security Posture 2

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

JSONSchema

JSONSchema

Scroll for all 8

Agent Surfaces 1

MCP servers, agent skills, and machine-readable catalogs

AgenticAccess

AgenticAccess

Design & Contract 2

Pagination, idempotency, versioning, errors, and events

Vocabulary

Vocabulary

JSONLDContext

JSONLDContext

Build 6

SDKs, sample code, and the tooling you integrate with

GitHubOrg

Examples

Examples

Examples

Examples

Examples

Access & Security 2

Authentication, authorization, and security posture

VulnerabilityDisclosure

VulnerabilityDisclosure

DomainSecurity

DomainSecurity

Operate 1

Status, limits, changes, and where to get help

RateLimits

RateLimits

Commercial 3

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

Other 1

Properties that don't map to a standard resource type

CapabilityMap

CapabilityMap

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.
deliveryModel:
  model: saas
  open_source: false
  commercial: true
  callable_host: true
  label: Hosted service · you call their endpoint
  confidence: high
  source:
  - openapi
  - pricing
  generated: '2026-08-28'
  method: derived
accessModel:
  pricing: free
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Free
  confidence: medium
  source:
  - plans
  - url: https://www.ecfr.gov
    status: 302
    note: declared website redirects to https://unblock.federalregister.gov/ — a different registrable domain (ecfr.gov ->
      federalregister.gov), possible rename or acquisition (probed 2026-09-03, roadmap#169)
  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: '0.23'
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: CapabilityMap
  url: capabilities/ecfr-capability-edges.yml
  name: eCFR Business Capability Map
- 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

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