> ## Documentation Index
> Fetch the complete documentation index at: https://docs.numeral.com/llms.txt
> Use this file to discover all available pages before exploring further.

# API Reference

> Explore the Numeral API for tax calculations

<Note>Make sure you generate an API key before making any requests. See [API Keys](/essentials/api-keys) for details.</Note>

## Overview

The Numeral API allows you to calculate and collect sales tax for your business. With our API, you can:

* Get tax information for products and addresses
* Record completed sales
* Handle refunds
* Manage products and customers

## Authentication

All API endpoints are authenticated using Bearer tokens. Include your API key in the Authorization header of all requests:

```bash theme={null}
curl --request POST \
  --url https://api.numeralhq.com/tax/calculations \
  --header 'Authorization: Bearer YOUR_API_KEY' \
  --header 'Content-Type: application/json' \
  --data '{ ... }'
```

## Base URL

All API requests should be made to:

```
https://api.numeralhq.com/
```

## API Versioning

The API is available in multiple versions:

* **2024-09-01** (default) - Base functionality
* **2025-05-12** - Enhanced with B2B support, tax IDs, automatic tax configuration, and more currencies

To specify an API version, include the `X-API-Version` header:

```bash theme={null}
--header 'X-API-Version: 2025-05-12'
```

If no version is specified, the default (2024-09-01) version is used.

For details on version-specific features, see the individual endpoint documentation.