The SEC EDGAR API is one of the best-kept secrets in financial data engineering: every mandatory disclosure filed by every U.S. public company, available as clean JSON, for free, with no API key. If you've ever paid for a "fundamentals" data vendor or scraped a brokerage page for a balance sheet, you've been working harder than you need to. The raw, authoritative source — quarterly revenue, insider trades, institutional holdings, 8-K event filings — is sitting on data.sec.gov waiting for an HTTP