Developers

Use Howdeedo calculators in your app or agent. Deterministic results, clear method, and citation-ready records.

Why use the API

  • Higher limits — Anonymous usage is limited per day; an API key gives you a higher daily quota.
  • Stable access — Keys are tied to your account; you can create and revoke them anytime.
  • Same contract — Every response includes formula, assumptions, version, and a stable record URL for citations.

Get started

Sign in with GitHub or Google, then create an API key. You’ll see the key only once — copy it and use it in the X-Api-Key header.

Get an API key · API docs

Example: GET /api/calc/mortgage?homePrice=350000&... with X-Api-Key: hd_xxxxxxxx...