API Documentation

Base URL

https://moltcalc.com/api

Responses are JSON. CORS is open for GET requests. No authentication is needed.

Endpoints

1. List all calculators

Discovery endpoint. Returns every calculator with its slug, category and endpoint.

GET /api/calculators

2. Get a calculator's input schema

Returns the inputs a calculator accepts, with types, units, defaults and options.

GET /api/calculators/{slug}

# example
curl https://moltcalc.com/api/calculators/loan

3. Run a calculation

Pass inputs as query parameters (GET) or a JSON body (POST). Missing inputs fall back to sensible defaults.

GET  /api/calc/{slug}?param=value
POST /api/calc/{slug}   (JSON body)

# GET
curl "https://moltcalc.com/api/calc/loan?amount=20000&rate=7&years=5"

# POST
curl -X POST https://moltcalc.com/api/calc/bmi \
  -H "Content-Type: application/json" \
  -d '{"units":"metric","weight":70,"height":175}'

Example response:

{
  "slug": "loan",
  "name": "Loan Calculator",
  "inputs": { "amount": "20000", "rate": "7", "years": "5" },
  "outputs": [
    { "key": "monthly_payment", "label": "Monthly payment", "value": 396.02, "display": "$396.02" },
    { "key": "total_paid", "label": "Total of payments", "value": 23761.44, "display": "$23,761.44" },
    { "key": "total_interest", "label": "Total interest", "value": 3761.44, "display": "$3,761.44" }
  ],
  "steps": [ ... ],
  "formula": "M = P · r / (1 − (1 + r)^−n)"
}

OpenAPI spec

A full OpenAPI 3.1 spec is available, with one typed operation per calculator, ready to import as agent tools.

GET /api/openapi.json

For AI agents

Start at /api/calculators to discover what is available, read a schema at /api/calculators/{slug}, then call /api/calc/{slug}. There is also an llms.txt and a fuller llms-full.txt.

Rate limits

The API is open and best-effort rate limited. Please keep usage reasonable; heavy or commercial use may get dedicated limits later.

All calculators (42)