Free calculator API for developers and AI agents

Every calculator is available as a free JSON API, every page as Markdown, and the whole site is described in llms.txt. No key, no sign-up, CORS open.

For AI agents

• llms.txt lists every calculator with a short description.
• Add index.md to any page URL for a clean Markdown version with the computed result, tables and sources.
• Calculator pages accept their inputs in the query string and render the result on the server, so a plain fetch of https://paycheck-math.com/us/paycheck-calculator/texas/?gross=85000 returns the computed numbers without JavaScript.

Endpoints

Run a calculator

GET https://paycheck-math.com/api/v1/calculate?path=/us/paycheck-calculator/texas/&gross=85000&filing=married

GET https://paycheck-math.com/api/v1/calculate?path=/ae/gratuity-calculator/&basic=12000&start=2019-03-01&end=2026-10-25&reason=resigned

Returns the inputs used, every line of the calculation, the headline figure and the date the rates were checked. The response lists inputs_accepted for that calculator.

Read the rules

GET https://paycheck-math.com/api/v1/rules?market=us&region=CA

Markets: us, uk, ca, au, de, gulf. Each rule set includes its official source URL.

List pages

GET https://paycheck-math.com/api/v1/pages?market=us&tool=paycheck

Live rates

GET https://paycheck-math.com/api/v1/rates

OpenAPI 3.1 description: https://paycheck-math.com/api/openapi.json

Fair use

Free for reasonable use. Please cache results and link back to the page you used. Results are estimates for information only.