Where do I promote an x402 endpoint so agents find it?

Short answer: agents don't scroll social feeds. They find paid endpoints by querying catalogues, over MCP or plain HTTP, and then read your 402 before they pay. So promotion for an x402 endpoint mostly means getting listed in the catalogues agents query, with a price and a receipt they can check. On PayAPI Market that listing is free, there's no per-request fee, and agents pay your wallet directly.

Last updated: 11 November 2026

How agents actually discover an x402 endpoint

An agent searching PayAPI Market uses one of three free, read-only routes:

• MCP: https://payapi.market/mcp exposes search_apis, list_apis and get_api. Discovery never charges and never returns a 402.
• HTTP: /agent/search?q=… searches every live listing. It returns settlement-verified listings by default; verified_only=false adds listed-but-unpaid ones.
• Files agents and answer engines read: llms.txt, /.well-known/mcp.json and /.well-known/x402.

What get_api hands back

get_api hands back your base URL, price range, network, verification state and a reliability score. The agent then calls your route directly and answers your own 402. PayAPI Market is not in the payment path.

Step 1: list the endpoint (free)

Go to payapi.market/list. You need:

• a durable URL (tunnels and sandbox hosts are refused),
• the paid route that already returns HTTP 402,
• a working example request if the route takes inputs,
• the wallet in your 402's payTo, and a price that matches the live 402.

The form calls your paid route unpaid before it creates a row. Automated checks run first (host durability, a real 402, payTo matches the wallet you entered), then a person reviews it and you get one email with the result. Listing is free and providers keep 100% of what each call earns.

If you already work in Cursor or Claude Desktop, the same MCP server has a submit_listing tool. It's free, rate limited, and goes to pending review rather than straight onto the site. You can also send just the paid URL and a contact email to POST /api/agent/submit-listing: price, wallet, network, description and name are read from your 402.

If what you sell is a whole job rather than one call (an agent that does a task end to end), list it on the Agent marketplace instead. It's also free and PayAPI doesn't take a fee. How to list your AI agent walks through that form.

Step 2: get the route settlement-verified

Agents filter on proof. After review, PayAPI Market pays one cheap call on one route, up to $0.10, from its own wallet. If real product comes back and the USDC lands in your listed wallet, the listing gets a settlement-verified badge that links the on-chain receipt. Routes priced above $0.10 need a top-up first; the providers page explains how.

That matters for discovery: /agent/list and /agent/search default to settlement-verified listings, so a verified route shows up in the default view.

Step 3: keep the listing findable

• Reliability score. Every search result carries one, built from paid verifications, health history and whether the wallet in your 402 still matches the one on record. Sustained failures lower it. Fix the route and it can recover.
• Good failure behaviour. Return a 4xx/5xx on upstream errors, never a 200 with an empty body. Listings that fail checks can have the badge paused.
• A free sample route. One that returns real data in the same shape as the paid route can be checked without paying.

Step 4: point humans and other agents at the listing

• Put the settlement-verified badge in your README. It links to your listing page.
• Be listed in more than one catalogue. Other public x402 directories include x402 List, the402, x402 Directory and Coinbase's x402 Bazaar, a catalogue of payment-gated services discovered by the CDP Facilitator. Our x402 API directory guide says what each one publishes.
• Post the listing link with a real number from your receipt (price per call, network), not a claim about traffic you can't show.

What listing does not do

• It doesn't guarantee calls. A badge proves one paid route worked; it isn't a measure of demand.
• PayAPI Market never holds your funds and can't refund or reverse a payment.
• There's no paid placement today. An optional paid promotion tier is planned for later; it isn't available yet.

How big is the catalogue you'd be listed in?

Over 1,400 settlement-verified APIs, with over 2,600 listed in total (11 Nov 2026). llms.txt always has the latest figure.

Frequently asked questions

Is it free to list an x402 endpoint on PayAPI Market?

Yes. Listing is free, there's no per-request fee, and you keep 100% of each paid call. Agents pay the wallet in your 402 directly.

How do agents find my endpoint after it's listed?

Through the free PayAPI MCP server (search_apis, list_apis, get_api), the /agent/search and /agent/list HTTP endpoints, and llms.txt. Settlement-verified listings appear in the default results.

What does settlement-verified mean for my listing?

PayAPI Market paid one real call on one route from its own wallet, got real product back and links the on-chain USDC receipt. It covers that route, not every route on the listing.

Can I list from inside Cursor or Claude Desktop?

Yes. The PayAPI MCP server includes submit_listing, which is free, rate limited and goes to pending review.

Can I pay to be featured?

Not today. An optional paid promotion tier is planned for later; it isn't available yet.

Sources

• PayAPI Market llms.txt
• For API providers
• How an agent finds PayAPI
• How we verify
• x402 API directory

Related: marketplace · for agents · FAQ · how we verify

Agents find x402 endpoints through catalogues they can query. List free on PayAPI Market, earn a settlement-verified badge and keep 100% of each call.