This article is part of our Agentic Commerce hub. Want help applying it? Talk to eSEOspace.
x402 is an open standard that lets a client, such as an AI agent, pay for a web resource inside an ordinary HTTP request. The server replies with a "402 Payment Required" status, the client pays, and the request goes through.
It is aimed at paying per request for APIs and online content. We would not treat it as a checkout replacement for a typical online store.
This guide is part of our Agentic Commerce hub. It was checked against the protocol's docs and the Linux Foundation's announcements on 9 November 2026.
This article is general information, not legal or financial advice.
Key Takeaways
- x402 uses the long-unused HTTP 402 status code to request payment programmatically.
- The Linux Foundation announced the x402 Foundation on 2 April 2026 and its operational launch on 14 July 2026.
- Coinbase created the protocol and completed its contribution to the Foundation.
- The docs say x402 does not natively support fiat off-ramps or credit-card deposits, though the Foundation describes support for card payment types.
- The docs describe the
exactscheme as a push payment that can't be reversed once executed, which changes how refunds work. - Stripe supports x402 only for USDC on Base, and its stablecoin payments exclude businesses in New York.
What HTTP 402 is
Every web response carries a status code. You've seen 404, meaning not found.
The x402 docs explain HTTP 402 this way. "HTTP 402 is a standard, but rarely used, HTTP response status code indicating that payment is required to access a resource." They say it was reserved for future use for decades.
The protocol FAQ puts it in one sentence. "x402 is an open-source protocol that turns the dormant HTTP 402 Payment Required status code into a fully-featured, onchain payment layer for APIs, websites, and autonomous agents." Onchain means the payment is recorded on a blockchain.
Why it exists
Selling API access has traditionally meant sign-up forms, plans and API keys. Those steps assume a person is present.
Stripe's machine payments page makes the same point. It says those flows need human input, which stops agents from completing tasks on their own.
x402 tries to remove those steps, so software can pay for one request at a time.
How an x402 payment works
The x402 repository sets out the flow. A simplified version looks like this:
- A client requests a resource from a server.
- The server replies
402 Payment Required, with payment details in aPAYMENT-REQUIREDheader. - The client picks an accepted option and builds a signed payment.
- The client retries the request with a
PAYMENT-SIGNATUREheader. - The server verifies the payment, either itself or through a facilitator.
- The payment settles, and the server returns the resource with a
PAYMENT-RESPONSEheader.
The repository notes that the first two steps are optional if the client already knows the payment details.
The README says servers have a lot of flexibility in this flow, so a real integration may differ.
Key terms
| Term | Plain meaning |
|---|---|
| Resource server | The server selling access to something |
| Client | The software paying, such as an agent |
| Facilitator | A service that verifies and settles payments for the server |
| Scheme | A way of moving money, such as a fixed amount or a capped amount |
| Stablecoin | A cryptocurrency pegged to another asset to limit price swings |
Payment schemes
The repository lists three schemes as of November 2026:
exacttransfers a specific amount, such as $1 to read an article.uptoauthorizes a maximum per request, and the seller settles actual usage up to that cap.batch-settlementis for EVM chains. It uses escrow and off-chain vouchers so many small charges can settle together.
EVM refers to Ethereum-compatible blockchains.
What a facilitator does
A facilitator is optional. The facilitator docs say "The facilitator is an optional but recommended service that simplifies the process of verifying and settling payments between clients (buyers) and servers (sellers)."
Using one means the server does not need its own blockchain connection. The repository adds a production warning: "Do not assume the public x402.org facilitator is the default production path for mainnet EVM routes."
Who runs x402 now
Coinbase created the protocol. The Linux Foundation announced the x402 Foundation on 2 April 2026 at MCP Dev Summit North America.
On 14 July 2026 it announced the operational launch and said Coinbase had completed its contribution of the protocol. The release says 40 organizations have joined as members.
Premier members named in that release include Adyen, Amazon Web Services, American Express, Circle, Cloudflare and Coinbase. Others are Fiserv, Google, Mastercard, Monad Foundation, MoonPay, Ripple, Shopify, Solana Foundation, Stellar Development Foundation, Stripe and Visa. Membership shows backing, but it does not show that each company has shipped an x402 product.
The FAQ says x402 is under the Apache-2.0 license, and that you don't need any Coinbase products to use it.
Crypto or cards? The sources differ
This point needs care, because the sources do not say quite the same thing.
The Linux Foundation release says the protocol supports payment types from traditional cards to stablecoins. The README says "It aims to support all networks (both crypto & fiat) and forms of value (stablecoins, tokens, fiat)."
The FAQ is narrower when asked about fiat off-ramps or credit-card deposits. "Not natively. However, facilitators or third-party gateways can wrap x402 flows with on- and off-ramps."
Our reading is that card support is a stated goal, and today's protocol is built around onchain payment. Check the current docs before you rely on either.
Limits a business should know
Refunds work differently. The FAQ is plain about this. "The exact scheme is a push payment—irreversible once executed." A seller makes a refund by sending a new transfer back to the buyer.
Agents need a wallet. Asked whether agents need wallets, the FAQ answers "Yes." Someone has to fund and manage that wallet.
Fees are not zero by default. The FAQ notes that gas is paid onchain, and that many facilitators offer zero facilitator fees. Gas is the network's transaction cost. Claims of low cost come from the project itself, so verify them for your network.
You take on crypto questions. Holding or accepting stablecoins can raise tax, accounting and licensing questions. We did not research those here. Ask a qualified adviser.
Using x402 through Stripe
Stripe supports x402, with limits. Its machine payments page says "Stripe also supports stablecoin payments over the x402 protocol."
The page says machine payments on Stripe work best with the Machine Payments Protocol (MPP), which can accept card and stablecoin payments. It lists x402 support for USDC on the Base network only.
Stripe's x402 guide sets a limit. "Stablecoin payments are available to businesses in all US states, except New York." Businesses outside the US must email Stripe to request access. You also have to request the Stablecoins and Crypto payment method, and Stripe reviews that request.
Our post on MCP payments, x402 and Stripe covers the MCP side in more depth.
Should your business care?
It depends on what you sell. x402 fits things that can be priced per request, such as an API, a data lookup or a single article.
If you sell physical products to shoppers, we'd put product data and checkout setup ahead of x402. Start with what agentic commerce is.
Next step
If you run an API or MCP server and want to charge per call, talk to our MCP development team about whether x402 fits. We can't promise revenue from it, and a payments specialist should review any live setup.
Frequently asked questions
Who owns x402?
Coinbase created it and completed its contribution to the x402 Foundation at the Linux Foundation. The Foundation announced its operational launch on 14 July 2026.
Is x402 only for crypto?
The docs say it does not natively support fiat off-ramps or credit-card deposits. The Linux Foundation describes support for payment types from cards to stablecoins, so check the current docs.
Do I need a Coinbase account?
The FAQ says you don't need any Coinbase products to use it.
Can a payment be refunded?
The FAQ says the exact scheme is irreversible once executed. A refund is a new transfer from the seller back to the buyer.
Does Stripe support x402?
Yes, for USDC on Base. Stripe's stablecoin payments are available to US businesses in every state except New York.
Do online stores need x402?
Not as a first step. It is built for paying per request, and store owners should fix product data and checkout first.
