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

# API Reference

> Complete reference for the Upwell REST API

## Welcome to the Upwell API

The Upwell REST API provides programmatic access to all core functionality of the
Upwell platform, including accounts payable automation, accounts receivable management,
and document processing for logistics and freight companies.

**Base URL**: `https://api.upwell.com`\
**Current Version**: 2.33.2\
**API Prefix**: `/api/rest/`

## Core API Modules

<CardGroup cols={2}>
  <Card title="Carrier Management" icon="truck" href="#carrier-endpoints">
    Manage carrier information, invoices, and payment processing
  </Card>

  <Card title="Customer Management" icon="users" href="#customer-endpoints">
    Handle customer profiles, payments, and billing operations
  </Card>

  <Card title="Vendor Management" icon="handshake" href="#vendor-endpoints">
    Manage vendor relationships, contracts, and payment terms
  </Card>

  <Card title="Shipment Tracking" icon="box" href="#shipment-endpoints">
    Track shipments, documents, and logistics data
  </Card>

  <Card title="Document Management" icon="file-text" href="#document-endpoints">
    Upload, process, and manage invoice and shipment documents
  </Card>

  <Card title="Bill Payments" icon="credit-card" href="#bill-payment-endpoints">
    Process bill payments and manage payment line items
  </Card>
</CardGroup>

## API Features

* **RESTful Design**: Standard HTTP methods (GET, POST, PUT, DELETE)
* **JSON Format**: All requests and responses use JSON
* **Authentication**: API key-based authentication
* **Error Handling**: Comprehensive error codes and messages
* **Rate Limiting**: Built-in rate limiting for API stability
* **Bulk Operations**: Efficient bulk processing for large datasets

## Authentication

All API requests must include your API key in the `Authorization` header.
See the [Authentication Guide](/authentication) for detailed instructions on obtaining
and using your API key.

```bash theme={null}
curl -X GET "https://api.upwell.com/api/rest/invoices" \
  -H "Authorization: YOUR_API_KEY"
```

## Response Format

All API responses follow a consistent format:

```json theme={null}
{
  "data": {},
  "status": "success",
  "message": "Request completed successfully"
}
```

## Getting Started

1. [Obtain your API key](/authentication#getting-your-api-key)
2. Review the endpoint documentation in the API Reference section
3. Test your integration using the provided examples
4. Implement error handling using our [troubleshooting guide](/troubleshooting)

For additional support, contact our [technical support team](mailto:support@upwell.com).