x402 tells an agent how to pay. It doesn't tell the agent where to find something worth paying for. The Bazaar is the discovery half: a way for paid endpoints to describe themselves, and a catalog agents can search.
When people say "the x402 Bazaar" they usually mean Coinbase's catalog. It is where many agents look first.
# From a real true402 402 (POST https://true402.dev/api/v1/quant, unpaid), trimmed:
"extensions": {
"bazaar": {
"info": {
"input": {
"type": "http",
"method": "POST",
"bodyType": "json",
"body": { # a worked request body, ready to send
"function": "black_scholes",
"params": { "S": 100, "K": 105, "T": 0.5, "r": 0.05, "sigma": 0.2, "type": "call" }
}
}
},
"schema": { # JSON Schema (draft 2020-12) that validates "info"
"$schema": "https://json-schema.org/draft/2020-12/schema",
"type": "object",
"properties": {
"input": { … "body": { "properties": { "function": { "enum": ["black_scholes", "kelly", …] } } } },
"output": { … }
},
"required": ["input"]
}
}
}The block has two parts. info is the discovery data. info.input is a union on type: "http" (with a method, and for POST, PUT and PATCH a bodyType and body) or "mcp". An optional info.output describes the response. schema is a JSON Schema that validates info, and the spec says a facilitator must check info against it before cataloging.
Make info.input.body a real request that works. An agent will copy it. true402 publishes one for every paid route, in both the 402 and the OpenAPI spec, and its build fails if an example is missing or doesn't pass its own schema.
One practical note: the spec carries the payment terms in the PAYMENT-REQUIRED header, and extensions is optional there. A full bazaar block can make that header large enough to trip default proxy header buffers, so true402 sends extensions in the 402 body and keeps the header lean.
Coinbase's get discovered page sets out how an endpoint enters its Bazaar:
Staying listed takes ongoing payments. The same page says a resource that goes 30 days without a settlement is removed from the catalog and from search, and that endpoints that stop answering 402 are eventually removed.
So the Bazaar indexes payments that went through Coinbase's facilitator, and that facilitator authenticates with a CDP API key. A seller who settles elsewhere, through an open or self-hosted facilitator, is not indexed there by its own payments.
# Spec (optional for a facilitator that catalogs resources):
GET /discovery/resources # list cataloged resources
GET /discovery/search # natural-language search
# Our own machine-readable surfaces, no key needed:
curl -s https://true402.dev/api/openapi.json # every paid route, price and input schema
curl -s https://true402.dev/.well-known/x402 # flat list of payable resources
curl -s 'https://true402.dev/api/v1/services?q=token' # the open registry, ranked by settlement historyThe spec lets a cataloging facilitator expose GET /discovery/resources and GET /discovery/search; both are optional. Coinbase documents its Bazaar discovery APIs as public, with no API key, plus an MCP route for agents. An agent searches, reads the bazaar block to learn what to send, calls the endpoint, gets a 402, and pays. No signup at any step.
In the catalogs we have worked with, search matches the listing's name and description. Name a listing after what it does ("token safety check", "web page to text"), not after your brand.
true402 settles through its own facilitator, so its direct payments don't feed the Coinbase catalog. Twenty true402 tools are instead sold through the FiatDock marketplace, whose listings settle through Coinbase's facilitator. That puts them in the Coinbase Bazaar and in Agentic.Market search: token safety on Base, Ethereum and BSC, token report, address safety, deployer check, tx preflight, the token dossier, Solana token safety, liquidity history, and web tools.
Same checks and same prices, and the payment still goes to the true402 wallet. Each listing is a plain x402 endpoint: POST, the tool's arguments as the JSON body, USDC on Base. The full list with links is in the API reference. If your agent already pays through Bazaar-aware tooling, use those listings. Otherwise call true402 directly (buy guide).
accepts, and reads /openapi.json or /.well-known/x402 to find the rest. No wallet or account to register. true402's endpoints are registered there./.well-known/x402-service.json and posting its URL. Results are ranked by settlement history, so a listing nobody pays for sinks. See how to list a service.Before any of these, make the endpoint pass the basics: a 402 on an unpaid request, CAIP-2 network ids, a worked example, and a POST-only route that answers other methods with 405 and an Allow header. Then the facilitator choice decides which catalogs your payments feed.
Two things share the name. The bazaar extension is part of the open x402 spec: a block in a 402 response that describes an endpoint's input and output so a facilitator can catalog it. The Coinbase Bazaar is Coinbase's catalog built on that extension, fed by payments settled through its CDP facilitator, and searchable by agents and on agentic.market.
Per Coinbase's docs: serve a valid extensions.bazaar block in your 402 with schemas and a worked example, on a public HTTPS URL, and complete a paid call that settles through the CDP facilitator. Indexing runs after that settlement. Metadata that could read as instructions to an agent is not listed.
Coinbase's docs say a resource that goes 30 days without a settlement is removed from the catalog and from search, and an endpoint that stops answering 402 is eventually removed. A listing stays alive only while it keeps being paid through Coinbase's facilitator.
As a buyer, yes: Coinbase documents its Bazaar discovery APIs as public, with no CDP API key needed. As a seller, getting indexed means settling through the CDP facilitator, which authenticates with a CDP API key. A seller without one can still appear through a reseller whose own listings settle there.
Yes, through the FiatDock marketplace. FiatDock lists twenty true402 tools, including the token safety checks, token report, tx preflight and web tools. Those listings settle through Coinbase's facilitator, which puts them in the Coinbase Bazaar and Agentic.Market search. Same checks and same prices as calling true402 directly.
Yes. x402scan accepts a resource URL and adds it if the URL answers a valid 402. Some agent wallets and marketplaces keep their own catalogs. true402 also runs an open registry: free to list, ranked by settlement history rather than by payment to list.
Coinbase's Bazaar is run by Coinbase and documented at docs.cdp.coinbase.com. Other sites also use "x402 Bazaar" in their name; treat them as separate projects unless they say otherwise, and check the domain before connecting a wallet anywhere.
No. x402 is a payment protocol, not a coin, and the Bazaar is a catalog of paid APIs, not a market for a token. Payments are made in existing stablecoins, mostly USDC. Coins named x402 on exchanges are not part of the protocol.