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BelfortData API

Belfort Data API

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The Belfort Data API serves company figures that come only from filings with the U.S. Securities and Exchange Commission: key metrics, financial statements as filed, segment revenue, insider trades, Form 13F holdings, filings lists, earnings releases, and two official macro series. It’s read-only, it answers in JSON, and an MCP server puts the same data in front of AI agents.

Two things set it apart. Every figure tells you which filing it came from, so you can open the filing and check it. And we publish how often our figures are wrong, with the sample sizes behind each number.

GET /v1/companies/AAPL/metrics?metric=revenueEach figure in the answer carries its own receipt. The shaded rows tie it to its filing.
value
The figure, as the filing states it. A blank in the filing is null, never 0.
period_end
The day the period ends, as filed.
concept
The XBRL tag the company filed it under.
source.accession
The filing it came from. source.filing_url opens it on EDGAR.
first_reported
The first filing to report this period, and what it said. A difference means a later filing changed it.
adjustments
Anything we did beyond copying one filed figure, with the reason.

Start here

Section titled “Start here”
  • Quickstart: from an API key to your first answer, in curl, Python or TypeScript.
  • Datasets: what each route returns, where it comes from, and what to watch for.
  • Where the data comes from: the SEC and BLS sources behind each dataset, and how a figure keeps its filing.
  • Quality: measured error rates, sample sizes and methods, including what we haven’t measured yet.
  • API reference: every route and field, with a console that sends real requests.
  • MCP server: use the data from Claude Desktop, Claude Code or another MCP client.

Base URL and your key

Section titled “Base URL and your key”

Base URL:

https://belfort-data-api.vercel.app

Send your key in the X-API-Key header on every route except /v1/status. A company can be named by ticker, in any case, or by CIK with or without leading zeros. The full rules are in Requests and responses.