No authentication is required; the eCFR API is a public REST API maintained by the Government Publishing Office.
Retrieve a specific CFR title and section via GET /api/versioner/v1/full/{date}/{title}.json, substituting an ISO date (or 'current') and the numeric CFR title.
Fetch a single section's XML structure via GET /api/versioner/v1/structure/{date}/title-{title}.json to get the table of contents hierarchy without the full text.
For full text search across regulations, use GET /api/search/v1/results?query=<term>&per_page=20&page=1; iterate pages to collect all results.
Parse the returned JSON or XML; sections are represented as hierarchical nodes with identifiers following the CFR part/section scheme (e.g., title 17, part 240, section 240.10b-5).
Known gotchas
The eCFR reflects the current codified text; it does not include proposed rules or recent final rules not yet codified — check the Federal Register API for those.
Historical versioning is available via the date parameter but only back to a certain year; do not assume complete historical coverage.
Regulation text is informational; always note that this output is not legal advice and that interpretation requires attorney review.
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