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

# x402

> Accept and make HTTP payments on Abstract using the x402 protocol.

[x402](https://x402.org) is an open payment standard that activates [HTTP 402 Payment Required](https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Status/402) for practical use.

It lets agents and applications charge for API access with a standard HTTP flow:

1. Client requests a paid resource
2. Server responds with `402 Payment Required`
3. Client signs a payment payload
4. Client retries with payment attached
5. A facilitator verifies and settles on-chain

## When to use x402

Use x402 when you want:

* the simplest pay-per-request integration path
* a public facilitator on Abstract
* a clean split between client and server middleware

Use [`MPP`](/ai-agents/payments/mpp/overview) instead when you want HTTP-native charge and session payment modes in one protocol, especially for repeated micro-payments.

## Abstract facilitator

Abstract runs a public x402 facilitator that any developer can use:

| | |
| - | - |
| **Facilitator URL** | `https://facilitator.x402.abs.xyz` |
| **Service fees** | None |
| **Gas fees** | Sponsored via paymaster |
| **Supported networks** | Abstract mainnet (`eip155:2741`), Abstract testnet (`eip155:11124`) |

## Supported token

The facilitator works with any [ERC-3009](https://eips.ethereum.org/EIPS/eip-3009)-capable token on Abstract. USDC is the recommended token:

| Network | Token | Address |
| - | - | - |
| Mainnet (`eip155:2741`) | USDC | `0x84A71ccD554Cc1b02749b35d22F684CC8ec987e1` |
| Testnet (`eip155:11124`) | USDC | `0xe4C7fBB0a626ed208021ccabA6Be1566905E2dFc` |

## x402 vs MPP

| | x402 | MPP |
| - | - | - |
| **Best for** | Fastest path to paid APIs | Charge plus session-based agent payments |
| **Primary model** | 402 challenge + facilitator settlement | HTTP-native method negotiation |
| **Repeated micro-payments** | Possible, but not the focus | First-class via session channels |

## Get started

<CardGroup cols={2}>
  <Card title="Accept x402 Payments" icon="server" href="/ai-agents/payments/x402/accepting-payments">
    Add payment middleware to your API.
  </Card>

  <Card title="Make x402 Payments" icon="credit-card" href="/ai-agents/payments/x402/making-payments">
    Build a client that can pay x402-protected resources.
  </Card>
</CardGroup>


This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.