What Is x402? How AI Agents Pay With Crypto

In brief

x402 is an open payment standard from Coinbase that uses the web's long-unused HTTP 402 code to let AI agents and apps pay for online services.

Payments are mostly made in USDC on Base and settled through facilitators, so buyers sign an authorization instead of creating accounts or API keys.

More than 50 companies, including Visa, Mastercard and Google, have joined the x402 Foundation, which now governs the protocol under the Linux Foundation.

Nobody really built the web with payments in mind. Early HTTP specifications included a status code, 402 "Payment Required", that was reserved for a future system of online payments. Then it sat unused for about 30 years. Payments were slow and expensive, and they needed accounts, card details and middlemen who could reverse charges. None of that works for a small payment made by software.

That gap matters more now because AI agents are starting to browse, call APIs and buy services for their users. An agent can't 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 it reports seeing a billion HTTP 402 responses on its network every day.

x402 is an attempt to finally give the internet a native way to pay. This guide covers what it is, how it works, who backs it, and whether there's a token involved.

Did you know?

The 402 "Payment Required" code has been in the HTTP standard since the 1990s. It was set aside "for future use", and x402 is the first big effort to actually use it.

What is x402?

x402 is an open payment standard built on top of HTTP, the protocol that moves data around the web. Coinbase launched it in May 2025 with partners including AWS, Anthropic, Circle and NEAR. It lets APIs, apps and AI agents pay for services in stablecoins as part of an ordinary web request.

x402 is not a blockchain and it is not a coin. It's a set of rules: message formats, headers and a request-and-response flow that any server or client can follow. Payments are mostly made in USDC, Circle's dollar-backed stablecoin, with Coinbase's Ethereum layer-2 network Base as the main settlement chain. The protocol works with any chain, though, and it now supports Solana, Polygon, Arbitrum and others, as well as traditional card payments.

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 new x402 Foundation became fully operational on July 14, 2026, and now stewards the protocol under vendor-neutral governance.

How does x402 work?

x402 works 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" and includes machine-readable terms: the price, which tokens it accepts and the wallet address to pay.

Payment: The client signs a payment authorization with its wallet and sends the request again with that signature attached in a header.

Delivery: The server checks the payment, settles it onchain and returns what was asked for.

Most of the onchain work is done by a facilitator, a service that verifies payments and settles them on the blockchain so sellers don't have to run their own crypto setup. On EVM chains, x402 uses EIP-3009, a standard that lets someone transfer tokens by signing a permission instead of sending a transaction themselves. This means the buyer doesn't need to hold ETH for gas.

What's so special about x402?

x402's main pitch is very small payments made by machines. Settlement on Base takes seconds and costs well under a cent, so it makes sense to pay fractions of a cent for a single API call. There's no sign-up, no API key and no subscription. The agent just pays and gets what it asked for.

Adoption has grown quickly. Coinbase released x402 V2 in December 2025, which added wallet-based identity so agents don't 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. x402 had processed more than 196 million transactions across 12 chains as of November 1, 2026, settling more than $42 million in total, according to Fireblocks, which cited data from tracker agenteconomy.to. Coinbase says more than 97% of onchain agent transactions in Q2 2026 used x402.

It's worth noting, however, 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, according to Fireblocks. Activity has since settled at a much lower level: in October 2026, x402 processed 5.1 million transactions worth about $274,000.

Who's 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 can 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.

Does x402 have a token?

No. 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 of them is issued or backed by Coinbase or the x402 Foundation. Be very wary of any token that claims to be the official x402 coin.

Where to buy USDC for x402 payments

To use x402, an agent or app needs a wallet holding a supported stablecoin on a supported network, usually USDC on Base. USDC is widely available on major exchanges including Coinbase, Kraken and Binance. Coinbase lets users send USDC straight to Base. Developers can also use Coinbase Developer Platform wallets or Circle Wallets to give their agents funds, and set spending limits to keep those agents under control.

The future of x402

The x402 Foundation is growing fast. It had 40 member organizations when it became operational in July 2026, and its member list has since grown to 57, including Visa, Mastercard, American Express, PayPal, Google, Shopify, Circle, Stripe and AWS. Michael Hursta became the foundation's executive director on October 1, 2026.

x402 isn't the only option, though. 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, it has also supported x402 payments. The big open question is whether x402's huge transaction counts turn into steady, real commerce. If they do, the payment code that sat unused for 30 years could end up carrying much of the AI economy's payments.