CFR Title Glossary API: All 50 CFR titles with names, searchable — Federal Register

All 50 CFR titles with names, searchable — subject to CFR title number in one call, feeding the CFR-part watch endpoints. Free, no key.

Free — no key, no signup, rate-limited to 60 calls per minute per client.

How do you call it?

GET /v1/regs/cfr-titles — product id reg_cfr_titles. Over MCP, call answerpool_get with product_id=reg_cfr_titles.

curl "https://answerpool.io/v1/regs/cfr-titles?q=energy"

Live call: https://answerpool.io/v1/regs/cfr-titles?q=energy · JSON sample: /v1/samples/reg_cfr_titles

What does the answer look like?

A representative response, the same static sample served at /v1/samples/reg_cfr_titles.

titles

{
 "as_of": "2026-09-03T02:00:00Z",
 "count": 1,
 "titles": [
  {
   "title": 10,
   "name": "Energy"
  }
 ],
 "watch_endpoint": "/v1/regs/cfr?title=<n>&part=<m>",
 "disclaimer": "Regulatory information from the Federal Register (public domain); not legal advice.",
 "refresh_after": "2026-09-18T00:00:00.000Z"
}

How fresh is it, and where does the data come from?

The fastest source behind this answer can change daily, so every response carries a refresh_after timestamp — right now it would be 2026-09-18T00:00:00.000Z. Schedule the next call on that value rather than on a guess.

• Federal Register (US federal public domain) — upstream: https://www.federalregister.gov/api/v1

Method version 0.1.0 · serving cache 30 days · every response carries a result_id you can resolve at /v1/provenance.

When should you use it?

You need to map a regulated subject to its CFR title, or decode one.

What you skip building

• govinfo CFR browsing
• title guessing

When should you not use it?

Actual rule documents — /v1/regs/cfr or /v1/regs/rules.

Where else can you find this?

• Catalog entry (JSON, free)
• OpenAPI schema — input and output types, prices, the 402 flow
• llms.txt — every product in one plain-text document