Buy and sell services with x402

What an x402 call is, and how to make one

A call is a request to a service: a price lookup, a document conversion, a search or another useful result. With x402, a service can charge for that request. It quotes a price and payment requirements; you decide whether to authorize the call. Check any additional access requirements and what the service promises to deliver.

The four steps, every time

1. Ask. Your agent sends the request. The service answers "402, payment required" and names its price, the network it wants paying on, and the wallet to pay.
2. Check. Before anything is signed, AIERC evaluates the wallet asking to be paid and the amount. The answer is CLEAN or FLAGGED. If the check cannot be completed, it is never treated as CLEAN — it is stopped the same way a FLAGGED one is. On FLAGGED, what happens is what you chose in your settings: stopped, or explained to you so you decide. Stopped is the default.
3. Pay. Your wallet asks you to authorize the quoted amount, network and receiving wallet. It may also ask for a separate message signature to establish your standing limit for paid calls. No key leaves your wallet. Review each prompt before signing.
4. Receive. The signed request goes to the service. Read the returned response and open the receipt to check the payment report, evaluation and delivery status. A payment report does not guarantee a useful answer. If the outcome is uncertain, check your receipt and wallet before paying again.

How to buy a call on this page

1. Connect your wallet in the header. This buying flow supports test tokens on Chaingentic Testnet and Base Sepolia. The service must accept the network and token you intend to use.
2. Find a service in the directory below, or paste a service address into Open the door.
3. Test-service cards check their price when they load; use Try the call to check again. For other directory entries, choose Check price and network. This price check does not make a payment. A Pay and call button appears when the reported requirements are compatible with this test site.
4. Choose Pay and call to request a quote and evaluation. Review the POS and each wallet prompt, including a standing-limit message if requested. A changed evaluation may require another decision before submission.
5. Read the returned response, then use View receipt for the payment report and evaluation. Recent call receipts keeps submitted-call links in this tab. Save a link if you need it after closing the tab. Available transaction and ITX links help you check the record.

The wider directory includes services on live networks that this test site cannot pay. Being listed does not confirm that a service is available or compatible. Check its current price and network. The direct-address form remains available if a directory cannot be loaded.

How to sell a call

1. You already have an API or a web service. Keep it.
2. Add the x402 payment layer in front of the routes you want to charge for. Use the official integration documentation for your application. Each protected route gets a price, a network and your receiving wallet.
3. Point it at a facilitator, the service that checks and settles the payment. Ours is https://facilitator.aierc.tech, and every payment through it is evaluated before it settles — check the currently supported payment options. Choose a compatible network and token, and test the complete payment and response path before offering the service.
4. Describe what one paid request delivers, in one plain sentence. A buyer's agent chooses by that sentence and the price.
5. Test it with your own wallet: ask, get the 402, pay, get the result. Then contact us about listing it; publication and a working connection need to be confirmed.

The step-by-step with code is in the x402 documentation: for buyers and for sellers. Our own machine-readable catalogue is at api.paygentic.online/.well-known/x402.