Plain-English explainer

What is x402?

x402 gives the internet a pay-per-use button: software can buy exactly what it needs, the moment it needs it, for pennies — with no signups, no subscriptions, and no invoices. Here's the whole idea in three minutes, no crypto background required.

The 30-second version

Everything useful on the internet sits behind a gate. To use a data service today, someone has to create an account, verify an email, enter a credit card, agree to a monthly plan, and manage an API key — fine for a person, impossible for software acting on its own.

That matters now because more and more work is done by AI agents: software that completes multi-step jobs without a human driving every click. An agent halfway through a task can't fill in a signup form or wait for procurement to approve a vendor.

x402 removes the gate. When software asks a paid service for something, the service answers with a price tag instead of a login screen. The software pays it — usually a fraction of a cent — and gets the result. The whole exchange takes about two seconds.

The name: the web's rulebook has included status code 402 — “Payment Required” since 1997, reserved for a future where the internet could handle payments natively. It sat unused for nearly three decades. x402 is that future, switched on.

Watch one payment happen

This is the entire protocol — four moves. Step through it:

one x402 purchase — live sequence

YOUR AGENTsoftware with a wallet

A PAID SERVICEdata · search · anything

agent → service: “What's the current price of NVDA?”

service → agent: 402 Payment Required · this answer costs $0.003

agent → service: same question + a signed 0.3¢ payment (like tap-to-pay)

service → agent: 200 OK · “NVDA: $182.41” · payment settled on-chain

RECEIPT · paid $0.003 · received 1 answer · time ~2 seconds · accounts created 0 · invoices 0

No account existed before this exchange and none exists after. The payment itself is the identity, the authorization, and the receipt.

“Agents paying agents” — the part that sounds like science fiction

Once software can buy things, software can hire things. An agent working on “research this company” can buy a stock quote from one vendor, a news search from another, and a document analysis from a third — three sellers, three payments of a few cents, zero business development.

It goes one layer further: an agent can pay another agent to do the choosing. This is a real purchase that ran through our marketplace router:

An actual receipt — agents paying agents, on-chain

A buyer's agent asked our router for DeFi market datapaid us $0.55

Our router picked the best proven seller (a firm we've never spoken to) and bought itwe paid them $0.01

Data delivered back to the buyer, both payments settled in the same 3-second window2 settlements

Humans involved at any step0

Every hop was real money with a public, verifiable record. Nobody exchanged contracts, sales calls, or API keys. That is the agent economy: services discovering, vetting, and paying each other at machine speed.

Why this matters for your business

A new kind of customer

Millions of AI agents are coming online that cannot fill in a signup form — but can pay. If your data or service is x402-enabled, they can become customers with no sales motion at all.

Meter anything

Anything you can serve over the web can be priced per use — a lookup for a tenth of a cent, a report for a dollar — without building billing, subscriptions, or collections.

Radically less friction

Settlement is final in seconds, refund-proof by design (no delivery, no charge), and global from day one. No chargebacks, no net-30, no dunning emails.

Executive FAQ

Is this a cryptocurrency investment thing?

No. Payments settle in USDC, a “digital dollar”: one USDC is one dollar, in and out. Nothing here is bought in the hope it goes up. x402 uses that digital dollar the way the web uses email — as infrastructure. The blockchain underneath is simply the settlement network that lets a one-cent payment clear in about two seconds for a fraction of a cent in cost, which card networks cannot do.

What does “agents paying agents” actually mean?

An AI agent is software that does a multi-step job on its own — research a company, monitor a market, process documents. Mid-job it constantly needs things it doesn't have: a stock quote, a web search, a page rendered. Today that means a human pre-registering for every vendor API. With x402, the agent just buys each piece the moment it needs it, for pennies, from whichever service answers best — including services run by other companies' agents. Software hiring software, with real money, no humans in the loop.

Who is behind x402? Is this a startup's proprietary thing?

x402 is an open protocol, not a product. It was created at Coinbase in 2025, and builds on a part of the web's own standard that has been reserved since 1997: HTTP status code 402, “Payment Required.” Anyone can implement it — our implementation is open source — and an ecosystem of independent sellers, marketplaces, and infrastructure providers is growing around it.

What does it cost to use?

Whatever the thing you're buying costs — typically fractions of a cent to a few cents per request — plus essentially zero payment overhead. No subscriptions, no minimums, no invoices, no chargebacks. A buyer who makes one call pays for one call.

What happens if a service takes the money and fails?

Payment and delivery are tied together at the protocol level: settlement completes only when a successful response is returned. If the service errors, the buyer is not charged. That guarantee is enforced by the payment flow itself, not by a refund department.

See it for real

Everything above runs live on this site: 500+ services priced in pennies, a public marketplace of independent sellers, and revenue you can verify on-chain.

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