All about Numbers. REST access with json/xml/jsonp result support. Below is the documentation for the Numbers API. You can try them out right here. Find more information and subscribe at math.tools
https://api.math.tools
Auth type
API Key Header
Auth header
X-Mathtools-Api-Secret: YOUR_API_KEY
Rate limit
Not officially published
Pricing
Enterprise / contact sales
Free quota
None
Documentation
https://api.math.tools
Endpoint status
Live — HTTP 200 — endpoint is accessible1.84s
(checked Mar 29, 2026)
Builder score
C
54%
builder-friendly
API key in the request header (X-Mathtools-Api-Secret)
X-Mathtools-Api-Secret: YOUR_API_KEY
Free and open. Number facts API (numbersapi.com); no paid tiers.
| Method | Path | Description |
|---|---|---|
| GET | /numbers/base |
Convert a given number from one base to another base |
| GET | /numbers/base/binary |
Convert a given number to binary |
| GET | /numbers/base/hex |
Convert a given number to hexadecimal |
| GET | /numbers/base/octal |
Convert a given number to octal |
| GET | /numbers/cardinal |
Get the cardinal of the given number |
| GET | /numbers/currency |
Spells out the number as a currency |
| GET | /numbers/fact |
Get a random fact about a number |
| GET | /numbers/is-cube |
Checks whether a given number is a cube number or not. |
curl -X GET 'https://api.math.tools/numbers/base' \ -H 'X-Mathtools-Api-Secret: YOUR_API_KEY'
{}
Data sourced from API Map. Always verify pricing and rate limits against the official Numbers documentation.