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x402

x402 is an open payment protocol that uses the HTTP 402 status code to enable per-request USDC payments on the web. Any website or API can require a small USDC payment before serving content. The ecosystem includes SDKs for building x402 clients and servers, infrastructure providers that handle payment verification, and integrations with major platforms. Most x402 activity runs on Base.

Exchanges
Wallets
DeFi
Payments
Bridgesx402

x402 Adopter Registry

Browse → sites, APIs, and services already accepting x402 USDC payments.

Editor’s picks

x402 Foundation logo

x402 Foundation

Editor’s pickIntegration

The open-source foundation governing the x402 protocol specification, documentation, and ecosystem coordination.

BaseEthereumSolana

Integration

1

Stripe x402

Stripe's x402 integration lets merchants accept per-request USDC payments alongside traditional card processing.

Base

SDK

4

Coinbase x402 SDK

The reference implementation for x402. TypeScript SDK for building clients and servers that handle per-request USDC payments.

BaseEthereumSolana

thirdweb x402

x402 middleware from thirdweb that integrates with their smart contract and wallet tooling.

BaseEthereum

x402 Python SDK

Python library for building x402 clients and servers. Ideal for AI agents and data services.

BaseEthereum

x402 Go SDK

Go implementation of the x402 protocol for high-performance servers and infrastructure.

BaseEthereum

Infrastructure

2

Kobaru

Managed x402 infrastructure. Handles facilitator duties so developers don't have to run their own payment verification.

BaseSolana

Cloudflare x402 Proxy

Cloudflare Workers template that adds x402 payment gates to any site deployed on Cloudflare's edge network.

Base

Related guides

What is x402?5 things you can do with USDC