x402
x402 is an open payment protocol that lets software, including AI agents, pay for APIs and digital services over HTTP using stablecoins, with no accounts, API keys, or manual signups. It revives the dormant HTTP 402 "Payment Required" status code so a server can request payment and a client can settle it programmatically inside a single request.
Updated June 24, 2026
x402 by the numbers
Live from x402scan- Transactions
- 181.8M
- Total volume
- $51.7M
- Unique buyers
- 826.6K
- Unique sellers
- 171.4K
On-chain totals as of June 24, 2026. Updated hourly.
How does x402 work?
When a client requests a paid resource, the server replies with an HTTP 402 response describing the price and where to send payment. The client pays in a stablecoin on-chain, then retries the request with proof of payment, and the server returns the resource. The whole exchange happens machine-to-machine in seconds, without a human creating an account or entering a card.
Who maintains x402?
x402 is an open standard. Its specification and reference implementation are developed in the open by Coinbase, so any developer or business can build on it.
Why does x402 matter for AI agents?
AI agents need to buy data and services at runtime, but traditional payments assume a human with an account and a credit card. x402 gives an agent a native way to pay per request, so it can discover a tool, pay for one call, and move on. This turns the long tail of APIs into something an agent can compose on demand rather than something a developer must integrate in advance.
What can an agent pay for with x402?
Anything that can be served behind an HTTP endpoint and priced per call. Merit Systems' x402scan indexes the live ecosystem of x402-enabled resources so agents can find them.
| Resource type | Example use |
|---|---|
| Data & enrichment APIs | Look up a company, person, or property record |
| Model inference | Run a single prompt through a hosted model |
| Compute & tools | Render, transcode, or scrape on demand |
| Premium content | Pay per article or per dataset download |
How is x402 different from traditional API payments?
Traditional API access requires signing up, getting an API key, and committing to a subscription before the first call. x402 removes that setup: payment is part of the request itself, settled per call in stablecoins.
| Dimension | Traditional API | x402 |
|---|---|---|
| Onboarding | Account + API key | None, pay in-request |
| Pricing | Monthly subscription | Per request |
| Who can pay | A human with a card | Any agent with a wallet |
| Settlement | Card networks, days | Stablecoins, seconds |
Frequently Asked Questions
- Is x402 a cryptocurrency?
- No. x402 is a payment protocol, not a coin. It defines how a client and server negotiate and settle a payment over HTTP. Payments typically settle in established stablecoins rather than a new token of its own.
- Do I need an account to use x402?
- No. The point of x402 is that no account or API key is required. A client pays per request directly from a wallet, which is what lets autonomous AI agents transact without a human in the loop.
- What is x402scan?
- x402scan is Merit Systems' index of the x402 ecosystem. It catalogs x402-enabled APIs and resources so that agents, and the people building them, can discover what is available to pay for and use.
- Why is it called 402?
- HTTP reserves status code 402 for "Payment Required," a code defined decades ago but left largely unused. x402 finally gives that code a concrete, open meaning for internet-native payments.