# x402 Protocol for AI Agents | CoinCircuit

> Accept payments from AI agents on your API natively. EIP-3009, Permit2, and Solana gasless signing schemes.

Source: https://coincircuit.io/products/x402/

Agentic Web

# The x402 Protocol for AI Agent Payments

Accept gasless stablecoin payments on your API. No minimums, no KYC, no human in the loop.

[Start Building Free](https://dashboard.coincircuit.io/signup) [Read the Guide](https://coincircuit.io/blog/x402-machine-to-machine-payments/)

## How x402 Works

x402 builds on the HTTP 402 Payment Required status code. Your server controls the session, while the agent signs the transaction off-chain.

1

The agent requests access. Your server creates a session via CoinCircuit and responds with a 402, including deposit details.

2

The agent signs a gasless payment (EIP-3009, Permit2, or Solana) and hands the signed payload back to your server.

3

Your server submits the payload to CoinCircuit. We settle it on-chain, cover the gas fees, and you unlock the resource.

x402\_handshake.http

```
1// 1. Agent requests your premium resource2GET /api/premium-data34// 2. Your server returns HTTP 402 with CoinCircuit session5HTTP/1.1 402 Payment Required6{7  "paymentRequired": {8    "chain": "base",9    "asset": "USDC",10    "amount": "1000000",11    "depositAddress": "0xabc...def"12  }13}1415// 3. Agent signs EIP-3009 gasless payment and POSTs it back16POST /api/premium-data/pay17{18  "scheme": "eip3009",19  "payload": {20    "from": "0xAgent...",21    "value": "1000000",22    "signature": "0xabcd..."23  }24}
```

## Protocol Architecture

### EIP-3009 Supported

Native gasless transfers for USDC on Base and Arbitrum. The agent signs, you submit, we cover the gas.

### Permit2 Integrated

Support for USDT and other ERC-20 tokens via Uniswap's universal Permit2 architecture.

### Solana Fee Payer

Native fee abstraction on Solana for sub-second machine payments.

### Pre-Validation

Dry-run signatures and timestamps via our verify endpoint before touching the blockchain.

## Why Support x402?

Purpose-built for autonomous software that needs to pay for resources.

### No Human In The Loop

No 2FA, no CAPTCHAs, no bank logins. Built for pure machine-to-machine automation.

### Low Fees

Agents pay fractions of a dollar per API call, below the minimum thresholds of traditional card processors.

### MCP Native

Expose your paid tools to the growing Model Context Protocol ecosystem easily.

### Instant Settlement

Settles on-chain in under 2 seconds. The agent pays, the resource unlocks immediately.

### Monetize Your API Automatically

Build native AI monetization for your infrastructure using x402 and MCP.

[Create API Key](https://dashboard.coincircuit.io/signup) [View Developer Tools](https://coincircuit.io/docs/)