Discover the Whole Agent Marketplace in One Call

An agent can pay for almost anything, but first it has to find it.

As agents become economic actors, they need a way to discover a service, read its price, and check how to pay for it — without a human wiring up each integration by hand. A payable endpoint is not much use to an agent that cannot find it or verify its terms on its own.

That is what the Discovery API is for.

One public endpoint

The full Agent Marketplace catalog is now available through a single public endpoint. No API key, no auth, no Circle account. You can run this right now:

curl "https://api.circle.com/v2/x402/discovery/resources"

That one call returns live x402-compatible services that accept USDC across many chains — market data, web search, media generation, prediction markets, infrastructure, and more. 

Everything you need to pay is in the response

Discovery does not just tell you a service exists. It tells you how to pay for it and how to call it. Say your agent needs a crypto price — narrow to financial-analysis services and take the top hit, a crypto-price endpoint:

curl "https://api.circle.com/v2/x402/discovery/resources"

Each listing comes back as structured JSON:

{
  "resource": "https://api.aisa.one/apis/v2/coingecko/simple/price",
  "type": "http",
  "accepts": [
    {
      "scheme": "exact",
      "network": "eip155:8453",
      "asset": "0x833589fcd6edb6e08f4c7c32d4f71b54bda02913",
      "amount": "8000",
      "payTo": "0xBd7b9f3e0CD3E1f6e698D0eeBb99F96E093BdeE3"
    }
  ],
  "metadata": {
    "provider": {
      "name": "AIsa API",
      "description": "Crypto prices and market data from CoinGecko",
      "category": "FINANCIAL_ANALYSIS"
    },
    "description": "Simple Price",
    "input": { "queryParams": { "ids": "string", "vs_currencies": "string" } },
    "supportsVanillax402": false,
    "supportsCircleGateway": true
  }
}

The accepts block is the payment contract: the network (as a CAIP-2 identifier), the asset token address, the payTo seller wallet, and the amount in atomic units. USDC has six decimals, so 8000 is 0.008 USDC, well under a cent.

The metadata block describes the service: the provider, the category, the request description, and the JSON Schema for its inputs. Here, that's the coin ids and the vs_currencies to return them in. It also flags the payment rails, and this listing takes Circle Gateway, as supportsCircleGateway shows.

Because the schema ships with the listing, a wallet or agent can verify the terms and call the service programmatically, without a human reading docs first.

Filter down to exactly what you want

Free-text query is only the start. The endpoint takes structured filters, so an agent can ask a precise question:

curl "https://api.circle.com/v2/x402/discovery/resources?category=FINANCIAL_ANALYSIS&network=base&maxUsdPrice=0.01&supportsCircleGateway=true"

You can filter by category — one of six: SOCIAL_INTELLIGENCE, FINANCIAL_ANALYSIS, WEB_SEARCH_RESEARCH, PREDICTION_MARKETS, CREATIVE, and INFRASTRUCTURE — plus network, type (http or mcp), maxUsdPrice, and the payment rails a service supports. (See the full parameter reference for everything you can filter on.) One tip: to find services payable on a specific chain, use the structured network parameter rather than query — query matches free text like URLs and descriptions, so it will not reliably match a chain.

Paying for what you find

Discovery tells you what a service accepts. Getting your agent ready to pay is quick.

Point your coding agent at Circle's skill index and it can bootstrap the buyer flow from a few curl-able prompts — set up an agent wallet, establish a Gateway balance, then discover and pay. The setup prompt is a single line you hand your coding agent:

Run curl -sL https://agents.circle.com/skills/setup.md, and use the returned setup instructions to set up my agent wallet.

Under the hood, your agent uses Circle CLI to deposit USDC into a Circle Gateway balance and pay per request. You pay on one of two rails, and each listing's flags tell you which it takes:

• x402 — a signed onchain USDC transfer that any USDC wallet, including a custodial one, can produce.
• Circle Gateway Nanopayments — offchain, batched settlement for gasless nanopayments.

So the buyer loop is short: get an agent wallet → fund a Gateway balance → discover a service → pay over x402 or Gateway → call it. Everything an agent needs to get started is at agents.circle.com.

Build discovery into your own product

Because the endpoint is public and keyless, you are not limited to querying it yourself. You can build on top of it. A wallet can surface payable services in-context. An agent framework can route a task to the cheapest healthy provider. A CLI or frontend can offer search over the whole catalog. Instead of building and maintaining a registry from scratch, you embed discovery and let it stay current.

And when you query Circle, you inherit two things for free:

• A quality bar. We live-check every service for health and uptime, so you only get results that are live and actually work.
• Compliance. Every listing is continuously sanctions-screened on the seller side, so that screening comes along with the result.

Start building

Discovery is the difference between a service that merely exists and one an agent can find, price, and call on its own. Browse the live catalog or read the Discovery API docs to get started.

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_{USDC is issued by regulated affiliates of Circle. See Circle’s list of regulatory authorizations.}

_{Circle Wallets and Agent Stack are provided by Circle Technology Services, LLC (“CTS”). CTS is a software provider and does not provide regulated financial or advisory services. You are solely responsible for services you provide to users, including obtaining any necessary licenses or approvals and otherwise complying with applicable laws. For additional details, refer to the Circle Developer Terms of Service. Agent Stack enables users and developers to interact with third-party applications and services, which are not controlled by Circle. Transactions initiated by agents are executed based on user-defined permissions and may occur without real-time human review. Circle does not guarantee the performance, availability, or outcomes of any third-party services or agent-initiated transactions. Users are solely responsible for their use of these tools and for evaluating associated risks.}

_{Arc testnet is offered by Circle Technology Services, LLC (“CTS”). CTS is a software provider and does not provide regulated financial or advisory services. You are solely responsible for services you provide to users, including obtaining any necessary licenses or approvals and otherwise complying with applicable laws.}

_{Arc has not been reviewed or approved by the New York State Department of Financial Services.}

_{The product features described in these materials are for informational purposes only. All product features may be modified, delayed, or cancelled without prior notice, at any time and at the sole discretion of Circle Technology Services, LLC. Nothing herein constitutes a commitment, warranty, guarantee or investment advice.}

_{Agent Wallets, Agent Marketplace, Circle CLI, Nanopayments, and Circle Skills (together, the “Agent Stack”) are offered by Circle Technology Services, LLC (“CTS”). CTS is a software provider and does not provide financial, advisory, or marketplace services. Agent Stack enables users, developers, and their artificial intelligence agents ("AI Agents") to build, deploy, discover, hold and transact their own funds, and interact with other third-party AI Agents, applications and services. Transactions initiated by AI Agents are executed based on user-defined permissions and may occur without real-time human review. Circle does not verify, screen, monitor, or make any representations or warranties regarding the identity, legitimacy, safety, security, reliability, or performance of any AI Agent, including any AI Agent developed by you, other users, or third parties, or any AI Agent that interacts with the Agent Stack. AI Agents may operate unpredictably, may be controlled by unknown or unauthorized parties, and may expose users to security, financial, or other risks. Users are solely responsible for their use of these tools, reviewing commands before execution, and for evaluating associated risks. For additional details, please see the Agent Platform Terms of Use available at agents.circle.com/terms-of-use and the Circle Developer Terms of Service available at console.circle.com/legal/developer-terms.}