How do I test that an AI agent can pay my API before launch?

You test it in three steps, from cheapest to most complete: you request your route with curl to see that it answers 402 with the payment offers, you run Peaje's mystery shopper to see whether an agent finds you and whether your payment step passes a strict client, and you make a small real payment from a wallet of your own. Peaje has no test network in production, so that last step moves real money, even if it is only cents.

Updated: November 2026

With a US$0.01 route on Arbitrum, the test costs you at most US$0.0202: you pay the price plus a network cost that never goes above US$0.02, and 98% of the price comes back to your payout wallet. Both limits are set in Peaje's contract on Arbitrum, which fixes the fee at 200 basis points (2%) and the maximum network cost at 0.02 USDC per payment.

How do I check the 402 by hand?

Before the first test, get three things ready:

• Your payout wallet, chosen in Revenue. Without it your routes answer 503 instead of 402, because the 98% has nowhere to go.
• Payments turned on. They start turned off, and while they are off, your priced routes answer for free and there is no 402 to test. You turn them on in Revenue with "Turn on payments", and they apply to all your priced routes and links at once, so from that moment any agent that arrives pays too.
• The kit on your domain, with PEAJE_ORIGIN_SECRET in your hosting's environment variables, as we explain in how do I charge AI agents for using my API.

If you want the whole thing to stay cheap, publish a route priced at US$0.01 just for the test. Then request the route twice without paying, on your domain and on Peaje's gateway, which is where the charge goes through even though the agent does not see it:

curl -i https://yourdomain.com/api/forecast/bogota
curl -i https://api.usepeaje.com/<your-slug>/api/forecast/bogota

Both should show the same thing:

If the gateway answers 402 and your domain does not, the problem is on your site: the proxy is not passing that route to Peaje, or a CDN or middleware is stripping the payment headers. When you decode payment-required, check two things strict x402 clients compare: that x402Version is 2 and that resource.url names your domain and not Peaje's. What each header carries is in what is 402 Payment Required.

What does the mystery shopper add?

It tells you what curl cannot: whether an agent would find you and whether it would pick you. It is part of the Pro plan, costs 30 credits, and you run it from My agent with "Test now" or by asking the agent in the chat. It gets three jobs your business should win, searches the Peaje directory, the x402 Bazaar and the ERC-8004 registries, and notes whether it found you, in what position, whom it picked and why. Then it requests your first priced GET route (or your first link, if you have no routes) without paying, on your domain and on the gateway, and checks it the way a strict client does. It needs at least one priced route or link, and how it decides is in how does an AI shopping agent choose which business to buy from.

Before launch it helps for three reasons:

• It separates your side from Peaje's. What you can fix on your site is left as a task, which closes on its own when the next test no longer sees the problem, and what belongs to the gateway is marked "On Peaje's side, nothing for you to do".
• Its requests do not count in Agent visits, so they do not inflate your payment funnel.
• If the test fails, or you ask for it before 6 hours have passed since the last one, you get the credits back.

It has one limit worth knowing: it never pays, so it does not prove the money reaches your wallet. That is what the next step is for.

How do I make a real test payment?

You pay, the way an agent would, from a wallet other than your payout wallet. Peaje's gateway runs on mainnet, as its public status shows, so you need USDC on Arbitrum One or pathUSD on Tempo. On Arbitrum you do not need ETH for gas, because you sign an authorization for the price plus the network cost and Peaje sends the transaction. On Tempo you pay the gas in your own transaction.

To pay, use an official client instead of building the headers by hand:

• MPP: mppx, the library from mpp.dev, with payment methods for Tempo and for EVM networks. It is the one Peaje uses in its own buying scripts.
• x402: @x402/fetch (or @x402/axios) together with @x402/evm, the packages in the x402 buyer quickstart, which pay the payment-required offer.

With the client set up, you request the route as you would with any fetch: the client gets the 402, pays and repeats the request. If it works, you get a 200 with your API's response and a receipt with the network and the transaction. Each agent speaks one of the two protocols, so test with the client the agent you expect will use, or with both if you do not know.

Then check your dashboard:

• Agent visits: your payment shows up as "MPP client" or "x402 client", depending on the client you used, and the "Payment funnel" shows your request under "402 served", "came back to pay" and "paid". Your curl calls also count as 402s served, and the mystery shopper's tests do not.
• Revenue: the payment with the date, the route, the network, the net amount and the "view tx" link to the transaction. The net is 98% of the price, and the network cost does not come out of it (how much Peaje keeps).

What do the errors I might see mean?

The body of each error has a code field that tells you what happened:

If your server fails after a payment on Tempo, Peaje refunds the agent, as we explain in what is 402 Payment Required.

Sources

• Peaje's contract on Arbiscan
• Peaje gateway status
• x402: quickstart for buyers
• mpp.dev: client quickstart
• mpp.dev: EVM payment method
• Peaje pricing