Obtain a free API key from api.data.gov; the key is passed in the X-Api-Key HTTP request header for all Regulations.gov v4 API calls.
Search for dockets using GET https://api.regulations.gov/v4/dockets?filter[searchTerm]={keyword}&api_key=YOUR_API_KEY; parse the docketId from results for subsequent calls.
Retrieve documents in a docket via GET https://api.regulations.gov/v4/documents?filter[docketId]={docketId}&api_key=YOUR_API_KEY; filter by documentType (Proposed Rule, Rule, Notice, Supporting Material) using filter[documentType].
To submit a public comment, POST to https://api.regulations.gov/v4/comments with a JSON body including commentOnDocumentId, comment text, and submitterType; file attachments require a prior call to retrieve a submission key.
For attachments, POST to the fileUpload endpoint to get a presigned URL, upload the file binary, then include the returned fileUploadId in the comment POST body.
The comment submission POST endpoint is rate-limited to 500 requests per hour; standard GET requests allow up to 1,000 per hour. Return status 429 with a Retry-After header signals rate exhaustion.
Known gotchas
The DEMO_KEY available without registration has very low rate limits (30 per hour, 50 per day) — always use a registered api.data.gov key for any production usage.
Comment submission closes at the precise deadline listed on the document; submissions received after the closing date may be accepted at agency discretion but are not guaranteed to be considered in the rulemaking record.
Regulations.gov v4 is the current API version; earlier versions are deprecated. Ensure your integration uses /v4/ path prefixes — prior route avoid-list entries using /v4/comments for retrieval are already covered; this route adds the submission and file attachment workflow.
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