Early access

OneCalc API

A simple REST API for unit conversion, live currency rates and engineering calculations.

GET/v1/units/categories

List all conversion categories and units.

POST/v1/units/convert

Convert a value between two units.

GET/v1/currency/rates

Latest exchange rates for 160+ currencies.

POST/v1/solar/calculate

Run any solar engineering calculator.

Example request

curl -X POST https://api.onecalc.app/v1/units/convert \
  -H "Authorization: Bearer <API_KEY>" \
  -H "Content-Type: application/json" \
  -d '{ "category": "length", "from": "m", "to": "ft", "value": 12 }'

Availability

The API is in private preview. Endpoints use JSON request and response bodies, bearer-token authentication and are rate limited to 60 requests per minute per key during the preview. Paths and payloads follow the shapes documented above and are versioned under /v1, so breaking changes will ship as /v2 rather than in place.

Want early access? Request an API key, or see the developer resources.