Full-text search the Code of Federal Regulations (eCFR) API

Search the live electronic CFR (GPO eCFR) and get matching regulation sections normalized with CFR citation, title/part/section, cleaned section heading, a plain-text excerpt, relevance score and effective date, plus a hits-by-title tally. Answers 'Which CFR sections regulate greenhouse gas?', 'Which titles carry most of the rules on this topic?'.

Price$0.01per request

MethodPOST

Route/v1/gov/ecfr-search

StatusLive

MIME typeapplication/json

Rate limit60/minute

Cache86400s public

govlegalregulationscfrecfrcompliancesearchus

API URLhttps://x402.hexl.dev/v1/gov/ecfr-search

Integration docs

Example request

{
  "query": "greenhouse gas",
  "limit": 3
}

Example response

{
  "query": "greenhouse gas",
  "totalMatches": 3353,
  "returned": 3,
  "hitsByTitle": {
    "40": 2,
    "48": 1
  },
  "results": [
    {
      "title": 48,
      "part": "223",
      "section": "223.501-70",
      "citation": "48 CFR 223.501-70",
      "sectionHeading": "Disclosure of greenhouse gas emissions.",
      "titleHeading": "Federal Acquisition Regulations System",
      "excerpt": "Definitions. As used in this section— Greenhouse gas means carbon dioxide, methane, nitrous…perfluorocarbons, or sulfur hexafluoride. Greenhouse gas inventory means, with respect to an…individual, a quantified list of the annual greenhouse gas emissions of the entity or individual",
      "score": 46.57,
      "effectiveDate": "2026-05-07"
    },
    {
      "title": 40,
      "part": "98",
      "section": "98.411",
      "citation": "40 CFR 98.411",
      "sectionHeading": "Reporting threshold.",
      "titleHeading": "Protection of Environment",
      "excerpt": "Any supplier of industrial greenhouse gases who meets the requirements of § 98.2(a)(4)",
      "score": 36.94,
      "effectiveDate": "2017-01-01"
    }
  ],
  "disclaimer": "Informational data product aggregated from public government / open-legal APIs. NOT legal advice. Verify against the official primary source before relying on it."
}

Input schema

{
  "type": "object",
  "required": [
    "query"
  ],
  "properties": {
    "query": {
      "type": "string",
      "description": "Regulation search phrase"
    },
    "title": {
      "type": "integer",
      "minimum": 1,
      "maximum": 50,
      "description": "Optional CFR title filter"
    },
    "limit": {
      "type": "integer",
      "minimum": 1,
      "maximum": 25,
      "default": 10
    }
  }
}

Output schema

{
  "type": "object",
  "additionalProperties": true
}