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

# API Reference

> Complete reference for all Zamp API endpoints.

The Zamp API provides endpoints for calculating sales tax, managing transactions, validating addresses, and accessing filing and registration data.

**Base URL:** `https://api.zamp.com`

## Authentication

All API endpoints are authenticated using bearer tokens in the `Authorization` header.

```bash theme={null}
curl https://api.zamp.com/transactions \
  -H "Authorization: Bearer {token}"
```

See the [Authentication guide](/guides/authentication) for details on obtaining a token.

## Conventions

<CardGroup cols={3}>
  <Card title="Errors" icon="triangle-exclamation" href="/guides/errors">
    Status codes and error response formats.
  </Card>

  <Card title="Pagination" icon="list" href="/guides/pagination">
    Work with cursor-paginated list responses.
  </Card>

  <Card title="Transaction object" icon="receipt" href="/guides/understanding-the-transaction-object">
    The shared shape behind calculations and transactions.
  </Card>
</CardGroup>

## Available endpoints

<CardGroup cols={2}>
  <Card title="Addresses" icon="location-dot" href="/api-reference/addresses">
    Validate addresses before collecting taxes
  </Card>

  <Card title="Calculations" icon="calculator" href="/api-reference/calculations">
    Calculate tax due on transactions in real-time
  </Card>

  <Card title="Companies" icon="building" href="/api-reference/companies">
    Retrieve company information associated with your API key
  </Card>

  <Card title="Transactions" icon="receipt" href="/api-reference/transactions">
    Create, retrieve, update, and delete transactions
  </Card>

  <Card title="Tax Codes" icon="tags" href="/api-reference/tax-codes">
    List all product tax codes supported by Zamp
  </Card>

  <Card title="Registrations" icon="file-certificate" href="/api-reference/registrations">
    View state tax registrations for your company
  </Card>

  <Card title="Filings" icon="file-invoice" href="/api-reference/filings">
    Access tax filing history and documents
  </Card>
</CardGroup>