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

# API Overview

> Introduction to the CoW Protocol Backend for Frontend API

# API Overview

The CoW Protocol BFF (Backend for Frontend) API provides a suite of services designed to enhance the user experience for frontend applications interacting with the CoW Protocol.

## Base URL

The API is accessible at:

```
https://api.cow.fi
```

For local development:

```
http://localhost:3001
```

## API Architecture

The BFF API is built on Fastify and provides endpoints organized into several key areas:

* **Tokens**: Token information, pricing, and holder data
* **Accounts**: User balances and allowances with real-time updates
* **Markets**: Slippage tolerance recommendations for trading pairs
* **Simulation**: Transaction simulation using Tenderly
* **Yield**: Pool information and APR data from various DEX protocols
* **Affiliate**: Affiliate program management and statistics
* **Notifications**: Push notification subscriptions and delivery
* **Hooks**: CoW Hooks analytics from Dune Analytics
* **Miscellaneous**: Utility endpoints including API version and proxies

## Chain Support

The API supports multiple blockchain networks. Chain IDs are specified in the path for most endpoints:

* `1` - Ethereum Mainnet
* `100` - Gnosis Chain
* `11155111` - Sepolia Testnet

Alternatively, you can use chain slugs:

* `mainnet` - Ethereum Mainnet
* `gnosis` - Gnosis Chain
* `sepolia` - Sepolia Testnet

## Response Format

All API responses are in JSON format. Successful responses return the requested data with appropriate HTTP status codes (200, 201, etc.). Error responses include a message field describing the error:

```json theme={null}
{
  "message": "Error description"
}
```

## Rate Limiting

The API implements caching headers to optimize performance. Check the `Cache-Control` header in responses to understand caching behavior.

## Getting Started

To get started with the API:

1. Choose the appropriate endpoint for your use case
2. Construct the request URL with the correct chain ID
3. Make an HTTP request (GET, POST, etc.)
4. Handle the JSON response

## API Documentation

Detailed documentation for each endpoint category is available in the following pages:

* [Authentication](/bff/api-reference/authentication) - No authentication required for public endpoints
* [Token Endpoints](/bff/api-reference/endpoints/tokens) - Token prices and holder data
* [Account Endpoints](/bff/api-reference/endpoints/accounts) - User balances with SSE support
* [Market Endpoints](/bff/api-reference/endpoints/markets) - Slippage tolerance calculations
* [Simulation Endpoints](/bff/api-reference/endpoints/simulation) - Transaction simulation
* [Yield Endpoints](/bff/api-reference/endpoints/yield) - Pool and APR information
* [Affiliate Endpoints](/bff/api-reference/endpoints/affiliate) - Affiliate program management
* [Notification Endpoints](/bff/api-reference/endpoints/notifications) - Push notifications
* [Hooks Endpoints](/bff/api-reference/endpoints/hooks) - CoW Hooks analytics data
* [Miscellaneous Endpoints](/bff/api-reference/endpoints/misc) - Utility endpoints

## Support

For issues or questions about the API, please refer to the [CoW Protocol documentation](https://docs.cow.fi) or reach out to the development team.