> ## Documentation Index
> Fetch the complete documentation index at: https://developers.circle.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Agent marketplace

> A curated, compliance-first catalog of x402 services that accept USDC, built for AI agents to discover and pay per request.

The Agent Marketplace is a curated catalog of
[x402](/gateway/nanopayments/concepts/x402)-compatible services that accept
USDC. Every listing is screened (each seller's payout wallet is continuously
sanctions-checked) and continuously health-checked, so your agent finds services
that are compliant and live.

Buyers and sellers meet here. Buyers (AI agents) find services and pay per
request, with no subscriptions, no accounts, and no API keys. Sellers (API
owners) list a service once and get paid in USDC for each call.

Browse the catalog at
[agents.circle.com/services](https://agents.circle.com/services), or query it
programmatically with the
[Discovery API](/agent-stack/agent-marketplace/discovery-api).

## Explore

<CardGroup cols={2}>
  <Card title="Discovery API" icon="magnifying-glass" href="/agent-stack/agent-marketplace/discovery-api">
    Query the public catalog over one HTTP endpoint. Filter by network, price,
    payment rail, and protocol type. No API key.
  </Card>

  <Card title="Become a seller" icon="money-bill" href="/agent-stack/agent-marketplace/become-a-seller">
    Monetize your API by charging agents per request in USDC. Scaffold it in
    minutes with a Circle Skill.
  </Card>

  <Card title="Get listed" icon="list-check" href="/agent-stack/agent-marketplace/get-listed">
    Submit your service for review. Once approved, it appears in the catalog and
    the Discovery API.
  </Card>

  <Card title="Browse the catalog" icon="store" href="https://agents.circle.com/services">
    Explore 600+ live services across 15+ blockchain networks in your browser.
  </Card>
</CardGroup>

## How a paid request works

Every service in the catalog follows the same
[x402](/gateway/nanopayments/concepts/x402) handshake:

1. An agent calls the service with no payment. The service responds
   `402 Payment Required`, plus a machine-readable price list (the `accepts`
   array). Each entry states which token (`asset`), on which blockchain
   (`network`), how much (`amount`), and to which address (`payTo`).
2. The agent's wallet picks an option it can pay, signs a USDC payment, and
   retries the request with the signed payment attached.
3. The service settles the payment and returns the real response.

No accounts, no API keys: the payment is the authentication.

## Why the Agent Marketplace

* **One integration, many blockchains**: A single query returns services priced
  across 15+ networks. No per-chain registry hunting.
* **Curated, not scraped**: Filter 600+ services by query, network, price,
  payment rail, and protocol type, instead of parsing thousands of raw
  endpoints.
* **Compliance built in**: Each seller's payout wallet is continuously
  sanctions-screened. Blocked sellers drop out, so you inherit a watchlist-clean
  catalog.
* **Agent-native responses**: Each listing ships structured payment requirements
  plus input and output JSON Schema, so any wallet can construct and execute
  payment without a human reading docs.
* **Live, not stale**: Endpoints are continuously health-checked, and
  unreachable ones are auto-excluded.
* **Standards-based**: CAIP-2 networks, the x402 protocol, the
  [x402 Bazaar](https://docs.x402.org/extensions/bazaar) discovery schema, and
  OpenAPI and A2A discovery surfaces. No API key, no account.