ecfr-io

eCFR.io provides free, read‑only JSON API and MCP server access to the Electronic Code of Federal Regulations (eCFR). Users can search, browse, and retrieve current and historical federal regulations without authentication. The service includes an OpenAPI specification, developer guides, and example usage, supporting cross‑origin requests for applications and AI agents.

ecfr-io publishes 3 API contracts indexed on the APIs.io network: Document API, Search API, and Titles API. Tagged areas include Government, Law, Regulations, API, and OpenData.

The ecfr-io catalog on APIs.io includes 1 Spectral governance ruleset.

ecfr-io’s developer surface includes documentation, API reference, getting-started guide, and 12 more developer resources.

🌐 Visit website 📡 Profile data on GitHub

28.0/100 thin Agent 27/100 agent aware Full breakdown ↓
scored 2026-10-31 · rubric v0.25.0 · Show this score on your site →

1 published contract

Government Law RegulationsAPIOpenDataFree

Kin Score

Kin Score How this is scored →
scored 2026-10-31 · rubric v0.25.0

Composite quality — 28.0/100 · thin

Contract Quality 8.7 / 21

Developer Ergonomics 6.0 / 17

Access Clarity 1.8 / 17

Operational Transparency 0.0 / 11

Contract Governance 1.9 / 10

Discoverability 5.3 / 9

Regulatory Posture 2.2 / 15

Agent readiness — 27/100 · agent aware

Machine-Readable Contract 18 / 18

Agentic Access Contract 10 / 10

Documented Reversibility 0 / 6

MCP Server 12 / 12

Machine-Readable Auth 0 / 10

Idempotency 0 / 9

Stable Error Semantics 8 / 8

Request/Response Examples 0 / 7

Rate-Limit Signaling 0 / 7

Typed Event Surface 0 / 6

Agent Skills 5 / 5

Well-Known Catalog 4 / 4

Consent & Bot Identity 0 / 3

A2A Agent Card 0 / 8

Dry-Run / Simulate Mode 0 / 4

Delegated User Identity 0 / 6

Protected Resource Metadata 0 / 5

Registration Without a Human 0 / 6

Agentic Commerce Well-Known Document 0 / 5

Pagination 5 / 5

Distinct Operations 3 / 3

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 could not be measured. We hold no machine-readable contract for this provider to read, so there is nothing to measure a write surface against. Excluded rather than scored zero: never-measured and measured-empty are different facts. Publishing an OpenAPI is what makes this facet — and several others — scorable at all.

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/.

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Agent readiness — checks not met, largest first (exact, from this profile):

Machine-Readable Auth +10 pts — a served openid-configuration/oauth-authorization-server carrying `issuer` (served), else the securitySchemes class in the provider OpenAPIs — bound (mutualTLS, DPoP, Signature) > negotiable (oauth2 authorizationCode/clientCredentials, openIdConnect) > bearer (http bearer, apiKey)
Idempotency +9 pts — OpenAPI mutating operations declare an idempotency key — a header, a request-body property, or a named de-duplication token whose own description says so (verified); else common[].type matches /idempoten/i (documented)
A2A Agent Card +8 pts — a2a/-a2a.yml manifest, graded on conformance.grade against A2A 1.0.0
Rate-Limit Signaling +7 pts — OpenAPI responses document X-RateLimit-* / RateLimit headers (verified), else a rate_limits artifact or RateLimits link (documented)
Request/Response Examples +7 pts — share of operations carrying request/response examples; else an Examples / Code Samples link
Delegated User Identity +6 pts — a served discovery document listing authorization_code in grant_types_supported (served), else an oauth2 authorizationCode flow or openIdConnect declared in an OpenAPI (documented)

7 more unmet checks in the Agent Readiness table above.

Kin Score — facets with the most composite points still available (weight × headroom):

Access Clarity scores 10.5 — up to +17.9 composite points
Contract Quality scores 41.0 — up to +14.8 composite points
Operational Transparency scores 0.0 — up to +13.0 composite points

Each check links to what satisfies it. Publish the artifact, or tell us where it already lives, and the score moves on the next scoring run.

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 the provider profile at artifacts.apis.io/ecfr-io/apis.yml: open an issue on github.com/api-evangelist/ecfr-io to ask a question or point us at an artifact you publish. 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-io Document API

The Document API from ecfr-io — 1 operation(s) for document.

ecfr-io Search API

The Search API from ecfr-io — 1 operation(s) for search.

ecfr-io Titles API

The Titles API from ecfr-io — 1 operation(s) for titles.

Spectral Rules 1

Spectral governance rulesets for linting and validating these APIs.

ecfr-io API Rules

11 rules · 9 errors 1 warnings 1 info

SPECTRAL

Security Posture 1

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

Ecfr Io Domain Security

TLSv1.3 · HSTS

SECURITY

Agentic Access 1

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

Ecfr Io Agentic Access

3 operations

3 operations · 0 acting

AGENTIC

Resources

Get Started 1

Portal, sign-up, and the first successful call

GettingStarted

GettingStarted

Documentation 2

Reference material describing how the API behaves

Documentation

Documentation

APIReference

APIReference

Agent Surfaces 4

MCP servers, agent skills, and machine-readable catalogs

AgenticAccess

AgentSkill

LLMsTxt

WellKnown

Design & Contract 3

Pagination, idempotency, versioning, errors, and events

Spectral

Spectral

ErrorCatalog

ErrorCatalog

Conformance

Conformance

Access & Security 1

Authentication, authorization, and security posture

DomainSecurity

DomainSecurity

Commercial 1

Pricing, plans, and the legal terms of use

PrivacyPolicy

PrivacyPolicy

Company 1

The organization behind the API

Website

Website

Other 2

Properties that don't map to a standard resource type

Hosts

Hosts

Vendors

Vendors

Source (apis.yml)

aid: ecfr-io
name: ecfr-io
description: eCFR.io provides free, read‑only JSON API and MCP server access to the Electronic Code of Federal Regulations
  (eCFR). Users can search, browse, and retrieve current and historical federal regulations without authentication. The service
  includes an OpenAPI specification, developer guides, and example usage, supporting cross‑origin requests for applications
  and AI agents.
url: https://artifacts.apis.io/ecfr-io/apis.yml
x-type: company
x-source: harvest:mcp-registry
x-tier: profiled
x-tier-reason: enrichment pass 2026-10-30 (modular-v1; was harvest)
specificationVersion: '0.20'
created: '2026-10-30'
modified: '2026-10-30'
tags:
- Government
- Law
- Regulations
- API
- OpenData
- Free
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
common:
- type: AgenticAccess
  url: agentic-access/ecfr-io-agentic-access.yml
- type: Spectral
  url: rules/ecfr-io-rules.yml
- type: AgentSkill
  url: skills/_index.yml
- type: ErrorCatalog
  url: errors/ecfr-io-problem-types.yml
- type: Conformance
  url: conformance/ecfr-io-conformance.yml
- type: LLMsTxt
  url: llms/ecfr-io-llms.txt
- type: WellKnown
  url: well-known/ecfr-io-well-known.yml
- type: Hosts
  url: hosts/ecfr-io-hosts.yml
- type: Vendors
  url: vendors/ecfr-io-vendors.yml
- type: DomainSecurity
  url: security/ecfr-io-domain-security.yml
- type: Website
  url: https://ecfr.io/
- type: Documentation
  url: https://ecfr.io/developers
- type: APIReference
  url: https://ecfr.io/openapi.json
- type: GettingStarted
  url: https://ecfr.io/about
- type: PrivacyPolicy
  url: https://ecfr.io/privacy-policy
apis:
- aid: ecfr-io:ecfr-io-document-api
  name: ecfr-io Document API
  description: The Document API from ecfr-io — 1 operation(s) for document.
  humanURL: https://ecfr.io/developers
  baseURL: https://ecfr.io
  tags:
  - Document
  properties:
  - type: OpenAPI
    url: openapi/ecfr-io-document-api-openapi.yml
- aid: ecfr-io:ecfr-io-search-api
  name: ecfr-io Search API
  description: The Search API from ecfr-io — 1 operation(s) for search.
  humanURL: https://ecfr.io/developers
  baseURL: https://ecfr.io
  tags:
  - Search
  properties:
  - type: OpenAPI
    url: openapi/ecfr-io-search-api-openapi.yml
- aid: ecfr-io:ecfr-io-titles-api
  name: ecfr-io Titles API
  description: The Titles API from ecfr-io — 1 operation(s) for titles.
  humanURL: https://ecfr.io/developers
  baseURL: https://ecfr.io
  tags:
  - Titles
  properties:
  - type: OpenAPI
    url: openapi/ecfr-io-titles-api-openapi.yml
x-enrichment:
  date: '2026-10-30'
  status: enriched
  artifacts_added: 24
  pass: modular-v1
  engine: identity=local,contract=local,surfaces=local,docs=local,regulatory=local

ecfr-io API — frequently asked questions

Does ecfr-io have an API?

Yes. APIs.io lists 3 APIs from ecfr-io, including ecfr-io Document API, ecfr-io Search API and ecfr-io Titles API.

Is there an OpenAPI specification for the ecfr-io API?

Yes. APIs.io indexes 3 OpenAPI specifications for ecfr-io, each linked for download from this page.

Is the ecfr-io API ready for AI agents?

ecfr-io has a Kin Score of 28.0 out of 100 (thin) and an Agent Readiness score of 27.3 (agent-aware), scored by API Evangelist on 2026-10-31.

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