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

# How the x402 payment protocol works with Laso

> Learn how the x402 HTTP payment protocol enables AI agents to pay for API requests with USDC stablecoin, replacing traditional API keys and subscriptions.

## What is x402?

x402 is an open payment protocol that uses the HTTP `402 Payment Required` status code to enable instant stablecoin payments over HTTP. Instead of API keys or subscriptions, you pay per request with USDC.

The protocol was created by Coinbase and is designed for both human users and AI agents.

## The payment flow

<Steps>
  <Step title="Request a protected resource">
    Your agent sends a normal HTTP request to a paywalled endpoint (like `GET
            /get-card?amount=50`).
  </Step>

  <Step title="Server returns 402">
    The server responds with `402 Payment Required` and a JSON body describing
    the price and how to pay.
  </Step>

  <Step title="Client signs a payment">
    Your x402 client library reads the payment requirements, constructs an
    EIP-3009 `transferWithAuthorization` payload, and signs it with your
    wallet's private key. No on-chain transaction is submitted — just a
    signature.
  </Step>

  <Step title="Client retries with payment header">
    The client replays the original request with an `X-PAYMENT` header
    containing the signed payment.
  </Step>

  <Step title="Server verifies and serves">
    The server forwards the payment to a **facilitator** (Coinbase) for
    verification. If valid, the server returns the requested resource and the
    facilitator settles the USDC transfer on-chain.
  </Step>
</Steps>

## The 402 response

When you hit a paywalled endpoint without paying, you get back a JSON body like this:

```json theme={null}
{
  "x402Version": 2,
  "accepts": [
    {
      "scheme": "exact",
      "network": "eip155:8453",
      "maxAmountRequired": "5000000",
      "resource": "https://laso.finance/get-card?amount=5",
      "description": "Get Laso Finance prepaid card",
      "payTo": "0x3291e96b3bff7ed56e3ca8364273c5b4654b2b37",
      "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913"
    },
    {
      "scheme": "exact",
      "network": "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp",
      "maxAmountRequired": "5000000",
      "resource": "https://laso.finance/get-card?amount=5",
      "description": "Get Laso Finance prepaid card",
      "payTo": "3MZVk97x9SeRxbYpc3jhzRfU2fyA3emYutnqfn9kNfYX",
      "asset": "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v"
    }
  ]
}
```

| Field               | Description                                                          |
| ------------------- | -------------------------------------------------------------------- |
| `scheme`            | Payment method — `"exact"` means pay the exact amount                |
| `network`           | Blockchain network in CAIP-2 format (`eip155:8453` = Base mainnet)   |
| `maxAmountRequired` | Amount in token base units (6 decimals for USDC, so `5000000` = \$5) |
| `payTo`             | Wallet address that receives the payment                             |
| `asset`             | USDC token contract address on Base                                  |

## Key concepts

### Your wallet signs, the facilitator pays gas

Your agent never submits a blockchain transaction. It only signs an authorization (EIP-3009 `transferWithAuthorization`). The facilitator — hosted by Coinbase — handles the on-chain settlement and pays gas fees.

### Client libraries handle everything

If you use `@x402/axios` or `@x402/fetch`, the entire 402 → sign → retry flow happens automatically. Your code looks like a normal HTTP request:

```typescript theme={null}
import { wrapAxios } from "@x402/axios";

const client = wrapAxios(axios, wallet);
// This looks like a normal request — x402 is handled under the hood
const response = await client.get("https://laso.finance/get-card?amount=50");
```

### Base mainnet + Solana mainnet (USDC)

Laso Finance accepts USDC payments on **Base** (Coinbase's L2) and **Solana mainnet**. Both networks have low fees and fast finality, making them ideal for the per-card payment flows on `/get-card`, `/order-gift-card`, `/get-push-to-card`, and `/order-intl-card`.

## The three actors

| Actor               | Role                                                   | Example                            |
| ------------------- | ------------------------------------------------------ | ---------------------------------- |
| **Client**          | Signs payment authorizations with a wallet             | Your AI agent using `@x402/axios`  |
| **Resource server** | Protects endpoints behind a paywall, verifies payments | Laso Finance API at `laso.finance` |
| **Facilitator**     | Verifies signatures and settles payments on-chain      | Coinbase's hosted facilitator      |

## Supported networks

x402 is chain-agnostic. The current ecosystem supports:

| Network        | CAIP-2 ID                                 | Token |
| -------------- | ----------------------------------------- | ----- |
| Base mainnet   | `eip155:8453`                             | USDC  |
| Solana mainnet | `solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp` | USDC  |

Laso Finance accepts payments on **Base mainnet** (`eip155:8453`) and **Solana mainnet** (`solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp`).

## Further reading

<CardGroup cols={2}>
  <Card title="x402 Protocol" icon="globe" href="https://x402.org">
    Official x402 protocol site and whitepaper.
  </Card>

  <Card title="x402 GitHub" icon="github" href="https://github.com/coinbase/x402">
    Open-source protocol specification and client libraries.
  </Card>
</CardGroup>