x402 is an open payment standard that activates HTTP 402 Payment Required for practical use. It lets agents and applications charge for API access with a standard HTTP flow:Documentation Index
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- Client requests a paid resource
- Server responds with
402 Payment Required - Client signs a payment payload
- Client retries with payment attached
- 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
MPP 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-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
Accept x402 Payments
Add payment middleware to your API.
Make x402 Payments
Build a client that can pay x402-protected resources.