Coinbase launched x402 in May 2025 as an open payment standard built on HTTP that lets AI agents and APIs pay for services in stablecoins without signing up or holding subscriptions. The protocol uses HTTP's long-unused 402 "Payment Required" status code, reserved since the 1990s, to enable frictionless machine-to-machine payments. Payments flow mostly through USDC on Base, Coinbase's Ethereum layer-2 network, though x402 now supports Solana, Polygon, Arbitrum and traditional card payments. Settlement takes seconds and costs under a cent per transaction.
The Linux Foundation launched the x402 Foundation on April 2, 2026, with Coinbase contributing the protocol. Initial supporters included Microsoft, Google, Visa and Mastercard. The foundation became fully operational July 14, 2026, and has grown to 57 member organizations including PayPal, Shopify, Circle, Stripe and AWS. Michael Hursta became executive director on October 1, 2026.
x402 is not a blockchain and has no official native token. Speculative "x402" tokens appeared on various chains but carry no backing from Coinbase or the foundation. Payments are made in existing stablecoins, primarily USDC.
Adoption grew rapidly through 2025 and 2026. Coinbase released x402 V2 in December 2025 with wallet-based identity and automatic service discovery, then added batch settlement in May 2026. The protocol processed over 196 million transactions across 12 chains as of November 1, 2026, settling more than $42 million total, according to Fireblocks data. However, more than half of lifetime transactions came from a two-month trading frenzy in late 2025 when automated scripts minted and sold PING token through x402. Activity dropped significantly after: October 2026 saw 5.1 million transactions worth about $274,000.
Coinbase reported that more than 97% of onchain agent transactions in Q2 2026 used x402. Competing standards include Stripe and OpenAI's Agentic Commerce Protocol and Visa's Trusted Agent Protocol, though both Stripe and Visa hold premier membership in the x402 Foundation.