Developer API
Free, public, CORS-enabled JSON API — every calculator on this site, callable from your own code.
…/api.php
POST · Content-Type: application/json
Send parameters as a JSON body to api.php?cat=<category>&action=<action>.
No API key, no rate limit enforced — this is a free demo API, please be reasonable with traffic.
Responses are JSON; on error you'll get {"error":"message"} with HTTP 400.
Endpoint Reference