# API overview

### Authentication - v402 Auth 3.0

The v402 Facilitator implements cryptographic authentication using **public keys** instead of traditional API keys:

#### Public Key Authentication

Your blockchain public key serves as your credential. Include it in requests:

```
Authorization: Bearer <your_public_key>
X-Public-Key: 0x1234567890abcdef1234567890abcdef12345678
X-Signature: <cryptographic_signature>
```

#### How It Works

1. **Generate a key pair** using your blockchain wallet (Ethereum, Solana, etc.)
2. **Use your public key** as your identifier
3. **Sign requests** with your private key for authentication
4. **All usage is paid** via x402 payment tokens, not stored points

#### x402 Payment Tokens

Usage credits are represented as **x402 payment tokens** - on-chain payment proofs that can be verified:

* No centralized point system
* Payments recorded on-chain
* Fully composable and transferable
* Tamper-proof accounting

#### x402 Payment Headers

For payment-related requests:

```
X-PAYMENT: v402.1.0:signature:payload:metadata
```

### API Endpoints Overview

| Category              | Endpoint Prefix | Purpose                                        |
| --------------------- | --------------- | ---------------------------------------------- |
| **Content Providers** | `/providers`    | Product management, analytics, payments        |
| **Index Clients**     | `/clients`      | Content discovery, access, payments            |
| **Administration**    | `/admin`        | System management, monitoring, user management |
| **Core Services**     | `/`             | Health checks, metrics, protocol discovery     |

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