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x402 is an open payment standard that activates HTTP 402 Payment Required for practical use. It enables any HTTP resource — an API, webpage, or file server — to require payment before serving a response, without custom billing infrastructure or payment integrations.

How it works

A typical x402 payment flow follows five steps:
  1. Client requests a resource — a standard HTTP request to a protected endpoint.
  2. Server responds with 402 — the response includes payment requirements (price, network, token, recipient).
  3. Client signs a payment — using their wallet, the client creates a signed payment payload matching the requirements.
  4. Client retries with payment — the original request is resent with the signed payment in a header.
  5. Facilitator verifies and settles — the server (via the facilitator) verifies the signature and settles the payment on-chain.
The client and server SDKs handle steps 2–5 automatically. From a developer’s perspective, it is one line of middleware on the server and one wrapper function on the client.

Abstract’s facilitator

Abstract runs a public x402 facilitator that any developer can use to accept and make payments on Abstract:
Facilitator URLhttps://facilitator.x402.abs.xyz
Service feesNone
Gas feesSponsored via paymaster — you pay nothing
Supported networksAbstract mainnet (eip155:2741), Abstract testnet (eip155:11124)

Supported tokens

The facilitator works with any ERC-3009-capable token on Abstract. USDC is the recommended token and is used throughout these guides:
NetworkTokenAddress
Mainnet (eip155:2741)USDC0x84A71ccD554Cc1b02749b35d22F684CC8ec987e1
Testnet (eip155:11124)USDC0xe4C7fBB0a626ed208021ccabA6Be1566905E2dFc

Key concepts

TermDescription
ClientThe entity making a request and paying for access to a resource.
ServerThe HTTP server that provides the resource and requires payment.
FacilitatorA service that verifies payment signatures and settles transactions on-chain.
SchemeThe payment logic — Abstract uses exact, which transfers a fixed amount per request.

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