The open‑source x402 standard lets AI agents and apps settle micro‑payments in stablecoins via HTTP 402 responses, with backing from Visa, Mastercard and Google.
Coinbase’s x402 protocol, launched in May 2025 and now governed by the Linux Foundation, provides an open‑source standard for AI agents and applications to pay for online services directly through HTTP requests. By reactivating the long‑unused HTTP 402 “Payment Required” code, x402 enables micro‑payments—typically in USDC—without the need for traditional checkout flows, API keys or subscription accounts.
When an AI agent requests a resource, the server returns a 402 response that includes the price, accepted token and a wallet address. The client then signs a payment authorization using its wallet and resends the request with the signature in a header. A facilitator verifies the payment and settles it on‑chain, after which the server delivers the requested data. The protocol leverages EIP‑3009 on EVM chains, allowing token transfers via signed permissions and eliminating the need for the buyer to hold ETH for gas.
As of 1 November 2026, x402 had processed over 196 million transactions across 12 blockchains, settling more than $42 million, according to Fireblocks data cited by Decrypt. Coinbase reports that 97 % of on‑chain agent transactions in Q2 2026 used x402. While a spike in late 2025—driven by automated token‑minting scripts—accounted for half of the protocol’s lifetime volume, activity has steadied, with 5.1 million transactions worth $274 000 recorded in October 2026.
The x402 Foundation, launched by the Linux Foundation on 2 April 2026, includes more than 50 members such as Visa, Mastercard, Google, Microsoft, AWS, Anthropic, Circle and NEAR. The foundation provides vendor‑neutral stewardship of the protocol, while co‑developers Cloudflare and Stripe contribute SDKs and edge‑gateway support. Settlement primarily occurs on Coinbase’s Base network, but the protocol also supports Solana, Polygon, Arbitrum and traditional card payments.
Future developments to monitor include the rollout of batch settlement features announced in May 2026, broader integration of x402 into AI‑agent SDKs from Cloudflare and Stripe, and potential expansion of supported tokens beyond USDC. Observers will also watch how regulatory bodies respond to machine‑to‑machine crypto payments as adoption grows across enterprise and consumer AI services.
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