← FORM4API

// about

About Form4API

Built and operated independently from Sweden.

What this is

Form4API is a developer-first REST API for U.S. SEC filings that move markets when insiders touch them: Form 4 insider transactions, Form 144 intent-to-sell disclosures, and 13F-HR institutional holdings. Real-time ingestion from EDGAR, amendment-aware parsing, post-trade returns, cluster-signal detection, and webhooks. Full reference.

Who built this

I'm Theodor Nielsen, founder of Form4API. I built and operate the service independently from Sweden.

Form4API exists because the data feeds that retail quants, financial newsletters, and IR teams used to rely on for insider-trading signals — IEX Cloud being the most prominent — have either been shut down, gated behind enterprise contracts, or degraded into licensing puzzles. The SEC publishes every Form 4 within two business days of an insider transaction, but the raw EDGAR feed isn't something you want to parse yourself. I built the infrastructure I wished existed.

Why trust this with your pipeline

  • Production-grade ingestion — EDGAR polled every 10 minutes, with priority queues for live filings and a separate worker pool for historical backfill.
  • 400+ backend tests (xUnit + Postgres integration suite) covering parsing, scoring, dispatch, and authorization. Test count and pass status surfaced internally on every deploy.
  • Stack is deliberately conservative: .NET 9 + PostgreSQL 16 on a single Hetzner CX23 dedicated host. Docker Compose for the runtime. No serverless gymnastics for the backend; the frontend ships on Vercel. Cheap, observable, fast to debug.
  • Open-source clients you can audit: MCP server, Sheets add-on, npm SDK, PyPI SDK.
  • Free tier exists because I was tired of API products that gate "free" behind a credit card. 500 requests/day, one read-only webhook, no card on file. Pricing.

Contact

Email: support@form4api.com. I read everything that comes through and reply within 24 hours on weekdays — slower on weekends.

Bug reports, feature requests, and integration questions on the open-source surface area are best filed as GitHub Issues — that's the channel I monitor most actively:

Legal

Form4API is operated independently from Sweden. Governing law for the API service is Sweden, with disputes venued in the courts of Stockholm — see the Terms of Service for the full statement. A formal business entity will be registered once the project moves out of the pre-revenue stage; this page will be updated with the registered name and Swedish organisationsnummer at that point.

Form4API is not affiliated with, endorsed by, or associated with the U.S. Securities and Exchange Commission (SEC) or EDGAR. All data is sourced from publicly available EDGAR filings. Not investment advice.