FERC eForms XBRL Submission API

The machine-to-machine API behind FERC's mandated eForms. Credentialed filers exchange their FERC eRegistration and Company Registration username and password for a bearer token at POST /api/token (OAuth2 password grant, role=filer), then POST a zipped XBRL submission to /api/SubmissionHistory/ExternalFiling with the company CID, report year, report period, and form identifier. FERC documents only that write path, but the API is not write-only — a second-round probe on 2026-07-27 found an undocumented ANONYMOUS read surface on the same host — GET /api/PublicSubmissionHistory (37,588 filing records, 10.6 MB, no key), /api/SubmissionDetail/{filingID} (accession number and attachment manifest), /api/SubmissionHistory/forms, /api/getTestStatus, /api/faq, and the full XBRL taxonomy release history at /api/TaxonomyHistory with its taxonomy packages, sample forms and release notes. Those endpoints are described in a DERIVED OpenAPI in this repo (FERC publishes none), built from FERC's own production JavaScript bundle plus its published Postman collection, with every path probed live. Verified 2026-07-27 — POST /api/token without valid credentials returns HTTP 400 with "Failed validating user in company registration", and the credentialed endpoints (/api/claims, /api/SubmissionHistory, /api/TaxonomyRevision) return HTTP 401.