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x402 payments

Pay-per-call crypto payments

Add x402 to your API and get paid in stablecoins for every call.

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What is x402

Payment built into HTTP

x402 is an open standard that lets any API charge for a single request. Your server answers an unpaid call with 402 Payment Required and a price. The buyer, an app or an AI agent, pays in stablecoins and repeats the call.

There is no sign-up, card or API key on the buyer's side, and no subscription to sell on yours. Cryptonly checks each payment, settles it on-chain and sends the money where you choose.

Priced per request
Set a price for each endpoint, down to half a cent.
No buyer accounts
Apps and AI agents pay from a wallet. Nothing to sign up for.
Open standard
Any x402 client can pay you, and the official x402 SDKs work as they are.
Use cases

What sellers charge for

  • 4020.01 USDC

    Market and data APIs

    Quotes, weather, maps or on-chain analytics, priced per call.

  • 4020.02 USDC

    Model inference

    Charge for each completion, embedding or image, with no subscription to sell.

  • 4020.005 USDT

    Tools for agents

    Search, scraping or code execution that agents call in the middle of a task.

  • 4020.50 EURC

    Articles and reports

    Sell a single article, dataset or report to readers and AI crawlers.

  • 4020.10 USDC

    Files and media

    Charge for downloads, renders and file conversions as they are requested.

  • 4020.05 EURC

    Premium endpoints

    Keep your free tier and charge only for the costly calls.

What Cryptonly brings

The parts you would otherwise build yourself

  • Signed webhooks

    Payment events, signed with your webhook key and retried if delivery fails.

  • Sanctions screening

    Payer and recipient are checked before every settlement.

  • Buyers need no ETH or SOL

    Cryptonly pays the network fee.

  • Networks and stablecoins

    Price each endpoint in the stablecoin you want to receive.

  • $0.0025per confirmed settlement

    Pay per settlement

    • First 100 settlements each month are free
    • Verify calls and failed settlements are free
Payouts

Choose where the money lands

Your own wallet or your Cryptonly balance. Switch any time without changing your code.

Where you get paid

Paid to
0x4b1f…a9e0Verified
FAQ

x402 questions

  • What is x402?

    x402 is an open standard for paying over HTTP. A server answers a request with 402 Payment Required and a price. The client signs a stablecoin payment and sends the request again with the payment attached.

  • What does an x402 facilitator do?

    The facilitator checks the buyer's signed payment and settles it on-chain, so your server needs no node, hot wallet or gas. Cryptonly is an x402 v2 facilitator with /verify, /settle and /supported endpoints, and adds payouts, webhooks and statements on top.

  • Does it work with the standard x402 SDKs?

    Yes. Pass CryptonlyFacilitatorClient to x402ResourceServer from @x402/express, @x402/hono or @x402/next. For Python, use the cryptonly-x402 package with the x402 SDK. Any client that supports x402 v2, such as @x402/fetch, can pay your endpoints.

  • How do AI agents find my API?

    Make an endpoint public in the dashboard and it appears in the discovery feed at GET /x402/discovery/resources, in the x402 Bazaar format. Agents and directories read that feed.

  • Do I need business verification?

    For production, yes: x402 turns on once your business verification (KYB) is approved. The sandbox is open to every account, so you can build and test first.

Selling an API to agents?

Tell us what you plan to charge for. We'll help with pricing, networks and setup.

Contact us