The x402 Service Directory: Discover and Submit Paid APIs for AI Agents

x402 lets an HTTP endpoint say how much a request costs, but the payment handshake begins only after a buyer has found the endpoint. Agents still need a practical way to discover services for a task. Providers still need a place where developers and agents can find the paid APIs they have already built.

The StableOps x402 service directory is built for both sides. Developers can browse, compare, and test published services. Providers can submit an x402 service and describe multiple endpoints under one listing. Before any payment, a visitor can request the live 402 challenge without connecting a wallet.

Why x402 needs a service directory

Traditional APIs are found through documentation, search engines, or integration marketplaces. Buyers then request a key, choose a plan, and fund an account. x402 moves the payment requirement into the HTTP exchange, reducing setup before settlement, but it does not automatically tell an agent which services exist, what they do, or whether an endpoint still returns a valid challenge.

The directory puts that discovery context in one place:

• Filter services by data, search, AI, compute, storage, content, and other categories.
• Search names, providers, descriptions, and endpoint URLs.
• Sort by 30-day transaction count, transaction volume, unique payer addresses, or newest listings.
• Review provider information, documentation, tags, endpoint descriptions, HTTP methods, and saved request templates.
• Request a real endpoint and inspect the 402 payment options it returns now.

A listing is not a purchase recommendation, and historical signals are not a service guarantee. The directory narrows the candidate set and surfaces useful integration details. The task, payment policy, budget, recipient allowlist, and approval rules should still determine whether an agent may pay.

Read the live 402 challenge before paying

One service can contain multiple endpoints. On its detail page, select an endpoint, review the saved method, query parameters, and example body, then choose Test 402. StableOps sends that request template to the service and displays the current payment options, including the atomic amount, asset, recipient, and payment timeout.

This action only reads the payment requirement. It does not connect a wallet or initiate an onchain payment. Use it to answer four questions before integration:

1. Is the endpoint reachable and returning a valid x402 challenge now?
2. Does its request template match the current task?
3. Do the network, asset, amount, and recipient satisfy your payment policy?
4. Which capability does each endpoint under the service provide?

The detail page also shows recent changes detected in payment requirements. When a probe observes a change to price, recipient, network, or x402 version, you can compare the previous and current values before paying. For a service that assigns recipients dynamically per quote, always use the address in the current quote.

Give software a machine-readable index

The website is useful for human evaluation. The public JSON endpoint lets tools and automated workflows retrieve candidates first. This request lists data services ordered by 30-day transaction count:

curl 'https://api.stableops.dev/v1/x402/resources?category=DATA&sort=TRANSACTION_COUNT&limit=10'

The response includes descriptions, providers, endpoints, categories, tags, timestamps, and available 30-day metrics. Software can use those fields to create a shortlist, but it should still read the chosen endpoint's live payment requirement and run its own policy, budget, and approval checks before purchase.

To configure controlled spending for an agent, continue with the Agent Payments quickstart. A runtime should discover and compare services, preview the exact URL and live quote, and reuse one stable idempotency key for retries of the same purchase.

Why providers should submit their services

A paid endpoint can earn usage only after buyers can find and understand it. A StableOps listing helps a provider:

• Explain the problem the service solves with a clear description, category, and tags.
• Group multiple endpoints under one service, each with its own method, parameters, and example request body.
• Link official documentation and reduce integration uncertainty.
• Let visitors read the live 402 requirement instead of relying on a static price that may be stale.
• Add available uptime, latency, and transaction context to the public detail page.
• Maintain submissions from My services while the current published version remains visible during review of an update.

Submitting a service is free, but you must create or sign in to a StableOps account and select your organization. The contact email is used for review and communication and is not published.

Prepare these details before submission

The submission form asks for the service name, provider, description, category, tags, contact email, and at least one endpoint. A documentation URL and submission note are optional.

For every endpoint, prepare:

• A public HTTPS URL without embedded credentials, a fragment, or a private-network host.
• An endpoint description that explains the returned result and suitable tasks.
• The correct HTTP method.
• Required query parameters and, where applicable, a body type and example request body.

Use Test 402 for every endpoint first. The system requests all endpoints again on submission. The service can be saved for review only when every endpoint returns a valid HTTP 402 payment requirement. An endpoint URL already listed under another service cannot be submitted again.

Avoid descriptions such as “data API” or “AI service.” A useful listing states the input, output, coverage, update frequency, and typical task. The saved request template should reproduce the payment challenge without containing real tokens, personal data, or other secrets.

Go from discovery to the first call

If you need a paid capability, browse the x402 service directory, choose a category, open a candidate, and test its live requirement first. Purchase through your x402 client or Agent Payments only after the task needs the result and the network, asset, amount, and recipient pass your controls.

If you already sell data, search, inference, compute, storage, or content through x402, submit your service. An accurate description, a reproducible request template, and a reliable 402 challenge help developers evaluate your API faster—and help agents discover it for the right task.