Where can an AI agent find x402 APIs?

Search a public catalog such as CDP Bazaar by the job the agent needs, then filter by network, asset and maximum price. Open the seller's canonical service page and machine contract before paying. A listing is a discovery lead, not proof that the endpoint is healthy or that its terms still match.

Can an MCP agent discover and call x402 services?

Yes. Coinbase documents Bazaar MCP as one interface to the same public catalog. A compatible client can discover services and handle payment through its own buyer workflow. A catalog or MCP listing does not give the service a buyer wallet or permission to spend.

Why can a successfully paid x402 API still be missing from Coinbase Bazaar?

Coinbase's current seller checklist requires a valid Bazaar declaration and one successful paid call through the CDP Facilitator for initial indexing. That paid call makes the route eligible; it does not guarantee immediate ranking or permanent visibility. Inspect EXTENSION-RESPONSES, allow for asynchronous cataloging and keep the live route healthy.

Does an x402 listing prove an API is safe to buy?

No. Verify the live endpoint, HTTP method, input schema, output contract, price, network, asset and payee. The live payment challenge should win over stale directory copy.

Editorial

Where to find an x402 API for a specific job

Search a public catalog for the job your agent needs. Then leave the directory and inspect the seller's canonical request, bounded output, live price and unpaid 402 challenge before a buyer-controlled wallet moves money.

zFinia published 9 September 2026 · updated 20 September 2026 · editorial guide

Choose by buyer job, not by directory badge

Describe the result the agent needs, such as checking field compatibility or fetching changes since a cursor.
Search the public catalog by that intent and apply network, asset and maximum-price filters.
Open the provider-owned service page and compare its input, output and limitations with the job.
Fetch the exact route without payment, inspect its 402 terms, and stop if the method, amount, asset, network or payee differs.
Only then may the buyer's own policy decide whether to authorize and retry the same request.

Browsing these pages and inspecting an unpaid challenge requires no zFinia account. A paid call requires an x402-capable client and a buyer-controlled wallet; this website does not hold that wallet or authorize payment.

Three live zFinia service jobs to evaluate

These examples are projected from zFinia's current seller catalog and matching OpenAPI contract. They are not generic directory copy, and catalog availability is not proof that a paid result was delivered.

Current service projection is unavailable. Use the provider-owned OpenAPI contract; no service availability or price is inferred here.

Start with these discovery surfaces

1. Circle x402 Discovery API

Circle opened its x402 Discovery API on 9 September 2026. The public endpoint requires no API key, authentication or Circle account and can be filtered by category, chain and price. That makes it a useful machine-native starting point for wallet-equipped agents looking for USDC-priced services.

Query Circle's x402 catalog

2. Coinbase x402 Bazaar and MCP

Coinbase's x402 Bazaar is a discovery layer for payable services. Its documented Bazaar MCP server gives compatible agents a semantic search tool for resources plus a proxy tool for invoking selected paid endpoints, bringing discovery and payment into an MCP workflow.

x402 Bazaar Bazaar MCP server

3. Base agent ecosystem

Base presents x402 as part of its agent-payment stack and points builders toward x402-enabled services and marketplace discovery. This is useful when the buyer already has a Base wallet or Base MCP workflow.

Base for agents

4. Independent x402 indexes

Independent directories can expose services that are easy to miss in one marketplace. Treat their counts, scores and verification labels according to each publisher's methodology rather than as universal market truth.

Market402 AgentIndex Agent402 marketplace

5. The provider's own machine surface

Once you find a candidate, go back to the seller. Look for its OpenAPI contract, service catalogue, agent metadata, MCP server or other machine-readable description. Discovery copy can lag the live endpoint.

Paid successfully but still missing from Bazaar?

Use Coinbase's current sequence instead of treating payment, indexing and ranking as one event. A valid route becomes eligible for initial indexing after one successful paid call through the CDP Facilitator; cataloging and ranking are later outcomes.

Run the public validation endpoint with the exact resource and method. No API key is required; continue only when it returns valid: trueand simulation.outcome: "accepted".
Confirm the route declares realistic input and output schemas so an agent can construct the call without guessing.
Confirm that one successful paid call actually went through the CDP Facilitator. A payment through another facilitator does not satisfy that documented indexing trigger.
Inspect the facilitator's EXTENSION-RESPONSES value for a Bazaar status of success, processing or rejected. Read any rejection reason before retrying.
Search the public catalog again after asynchronous processing. Ranking is recomputed separately from indexing and uses recent usage plus listing quality.

A seller-funded payment may test eligibility, but it is not independent demand or revenue. Repeated self-payments are not a substitute for fixing a rejected declaration or earning real usage.

Coinbase seller discovery checklist Coinbase buyer discovery guide Full Bazaar troubleshooting guide →

What to verify before an agent pays

The endpoint and HTTP method are live.
The input schema is explicit enough to call without guessing.
The expected output is documented and machine-verifiable.
The live 402 names the price, network, asset and payee you expect.
The service's freshness, provenance and usage constraints fit the job.
The buyer has a bounded wallet policy and can retry the same request after payment.

A directory entry is not a settlement receipt. An unpaid 402 is not revenue. For machine buyers, the useful path is discover → understand → select → pay → verify → reuse.

What makes an x402 service easier for agents to select

Discovery is increasingly query-driven. A seller is easier to evaluate when its service description names the buyer outcome, its OpenAPI or MCP schema is callable without guesswork, and its live 402 exposes stable payment terms. Health, freshness and provenance signals help an agent distinguish a useful service from a stale listing.

For zFinia itself, the public agent card, x402 discovery document, OpenAPI contract and MCP surface are available directly from the machine API so an agent can verify the owned source rather than relying only on third-party directory copy.

zFinia agent card zFinia x402 discovery zFinia OpenAPI zFinia MCP

Use zFinia as the research layer

The zFinia directory tracks payment protocols, wallets, networks and infrastructure with source links and verification dates. Machines can use the API and discovery surfaces directly.

Open the machine-economy directory →Open the machine API →