x402 is an open payment standard from Coinbase that uses HTTP's long-dormant 402 "Payment Required" status code to let AI agents and applications pay for online services, mostly in USDC on the Base network. The protocol is designed for machine-to-machine payments too small to justify accounts, card details or subscriptions.
The 402 code has been part of the HTTP standard since the 1990s, reserved "for future use." It sat largely unused for about 30 years. Coinbase launched x402 in May 2025 with partners including AWS, Anthropic, Circle and NEAR.
How the payment flow works
x402 is not a blockchain or a coin. It is a set of rules covering message formats, headers and a request-and-response flow that any server or client can follow. A typical transaction runs through a short handshake inside a normal web request:
- Request: An AI agent or app asks a server for something, such as an API call, a dataset or an article.
- 402 response: The server replies "402 Payment Required" with machine-readable terms, including the price, accepted tokens and the wallet address to pay.
- Payment: The client signs a payment authorization with its wallet and resends the request with the signature attached in a header.
- Delivery: The server checks the payment, settles it onchain and returns the requested item.
Most of the onchain work is handled by a facilitator, a service that verifies and settles payments so sellers do not need to run their own crypto infrastructure. On EVM chains, x402 uses EIP-3009, which lets a buyer transfer tokens by signing a permission rather than sending a transaction, so the buyer does not need to hold ETH for gas.
Payments are mostly made in USDC, Circle's dollar-backed stablecoin, with Base as the main settlement chain. The protocol works with any chain and now supports Solana, Polygon, Arbitrum and others, as well as traditional card payments.
Why small machine payments matter
x402's main pitch is very small payments made by machines. Settlement on Base takes seconds and costs well under a cent, making it practical to charge fractions of a cent for a single API call. There is no sign-up, API key or subscription.
The gap matters more as AI agents browse, call APIs and buy services for users. An agent cannot fill in a checkout form or sign up for a monthly plan for every tool it uses. Cloudflare says more than half of internet traffic is now non-human and reports seeing a billion HTTP 402 responses on its network every day.
Adoption and governance
Coinbase released x402 V2 in December 2025, adding wallet-based identity so agents do not have to pay again on every call, automatic service discovery and support for more chains. In May 2026 it added batch settlement, where agents hand sellers signed vouchers that can be settled in bulk.
According to Fireblocks, citing data from tracker agenteconomy.to, x402 had processed more than 196 million transactions across 12 chains as of November 1, 2026, settling more than $42 million in total. Coinbase says more than 97% of onchain agent transactions in Q2 2026 used x402.
Fireblocks noted that more than half of x402's lifetime transactions came from a two-month frenzy in late 2025, when traders ran automated scripts to mint and sell PING, a token issued through x402. Activity has since settled at a lower level: in October 2026, x402 processed 5.1 million transactions worth about $274,000.
On April 2, 2026, the Linux Foundation announced it was launching the x402 Foundation, with Coinbase contributing the protocol and companies including Microsoft, Google, Visa and Mastercard expressing initial support. The foundation became fully operational on July 14, 2026, and now stewards the protocol under vendor-neutral governance. It had 40 member organizations at that point, and its member list has since grown to 57, including Visa, Mastercard, American Express, PayPal, Google, Shopify, Circle, Stripe and AWS. Michael Hursta became executive director on October 1, 2026.
Who is working with x402
- Cloudflare: co-developer of the x402 Foundation with Coinbase and Stripe, with x402 support in its Agents SDK and a monetization gateway that runs at the network edge.
- Stripe: co-developer of the x402 Foundation and a premier member that turns x402 payments into its standard PaymentIntents, so merchants get familiar reporting and payouts in regular currency.
- Agentic.Market: Coinbase's public marketplace, launched in April 2026, for discovering and comparing x402 services, with live pricing and volume data.
- CoinGecko: offers crypto market data API endpoints that agents pay for per call.
- AWS: its AgentCore service manages agent payments, budgets and permissions on the buyer side.
- Google: its agent-to-agent (A2A) x402 extension, part of its Agent Payments Protocol (AP2) and built with Coinbase, the Ethereum Foundation and MetaMask, uses x402 for crypto settlement between agents.
No official token
x402 is a protocol, not a cryptocurrency, and it has no official native token. Payments are made in existing stablecoins, mostly USDC. Speculative "x402" tokens have appeared on various chains, but none is issued or backed by Coinbase or the x402 Foundation.
To use x402, an agent or app needs a wallet holding a supported stablecoin on a supported network, usually USDC on Base. USDC is available on major exchanges including Coinbase, Kraken and Binance, and Coinbase lets users send USDC directly to Base. Developers can also use Coinbase Developer Platform wallets or Circle Wallets to fund agents and set spending limits.
Competing standards
x402 is not the only option. The Agentic Commerce Protocol, an open standard developed by Stripe and OpenAI, and Visa's Trusted Agent Protocol are competing for a role in agent payments, even though Stripe and Visa are also premier members of the x402 Foundation.
Stripe has also co-developed the Machine Payments Protocol with payments blockchain Tempo. Like x402, MPP uses the HTTP 402 code to let agents pay for services, but adds session-based billing so agents can pay as they go rather than settling every request onchain. Since June 2026, MPP has also supported x402 payments.
The open question is whether x402's large transaction counts turn into steady, real commerce.
