> ## 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.
# Discovery API
> One public endpoint to discover x402 services that accept USDC, across many blockchains. No API key, no account.
The Discovery API returns [x402](/gateway/nanopayments/concepts/x402)-compatible
services that accept USDC, across 15+ blockchain networks, from one public
endpoint. It powers the [catalog UI](https://agents.circle.com/services) and is
open for any client, wallet, or agent to query directly.
The catalog is curated and continuously sanctions-screened on the seller side,
and every listing carries structured payment requirements and JSON Schema, so
any wallet can pay for and call a service on top of x402. See the
[marketplace overview](/agent-stack/agent-marketplace) for the full rationale.
## Endpoint
```http theme={null}
GET https://api.circle.com/v2/x402/discovery/resources
```
This endpoint is public. It needs no authentication, no API key, and no Circle
account. Responses support `gzip` compression, so pass `--compressed` when you
call it with `curl`.
## Query parameters
All parameters are optional. Combine them to narrow the catalog to exactly the
services your agent can use.
| Parameter | Type | Description |
| :---------------------- | :------ | :------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| `query` | string | Fuzzy search across resource URLs, providers, descriptions, and tags. |
| `type` | string | Protocol type: `http` or `mcp`. |
| `category` | string | Service category, one of the six values in [Categories](#categories) (for example, `FINANCIAL_ANALYSIS`). |
| `network` | string | CAIP-2 identifier (for example, `eip155:8453`) or a legacy SDK name (for example, `base`, `base-sepolia`). Only EVM chains have legacy aliases; Solana must use its full CAIP-2 identifier. |
| `asset` | string | Payment token contract address. |
| `scheme` | string | Payment scheme (for example, `exact`). |
| `payTo` | string | Merchant (seller) wallet address. |
| `maxUsdPrice` | number | Maximum price per request in USD (for example, `0.01`). |
| `supportsVanillax402` | boolean | `true` returns endpoints that support vanilla x402 (onchain payments). |
| `supportsCircleGateway` | boolean | `true` returns endpoints that support Circle Gateway (offchain, batched payments). |
| `siwx` | boolean | `true` returns only SIWX (Sign-In With X, browser-auth) endpoints; `false` excludes them; omit to return all. Use `false` for CLI or automation. |
| `fields` | string | Comma-separated list of fields to include in each item. |
| `limit` | integer | Number of items to return. Default `50`, maximum `200`. |
| `offset` | integer | Number of items to skip, for pagination. Default `0`. |
## Response
The response follows the [x402 Bazaar](https://docs.x402.org/extensions/bazaar)
discovery schema, the discovery format standardized as an x402 v2 extension.
Clients built against another Bazaar-compatible catalog can parse this one
unchanged.
A successful call returns a JSON object with three top-level fields:
* `x402Version`: the x402 protocol version the response follows.
* `items`: an array of service listings (described below).
* `pagination`: the `limit`, `offset`, and `total` count for the query.
```json theme={null}
{
"x402Version": 2,
"items": [
{
"resource": "https://api.aisa.one/apis/v2/coingecko/simple/price",
"type": "http",
"x402Version": 2,
"lastUpdated": "2026-06-25T16:40:14.015Z",
"accepts": [
{
"scheme": "exact",
"network": "eip155:8453",
"asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
"amount": "10000",
"payTo": "0x5aAeb6053F3E94C9b9A09f33669435E7Ef1BeAed",
"extra": { "name": "USD Coin", "version": "2" }
}
],
"metadata": {
"provider": {
"name": "AIsa API",
"description": "cryptocurrency market data prices",
"category": "FINANCIAL_ANALYSIS",
"tags": ["x402", "crypto", "market-data"],
"website": "https://aisa.one",
"docsUrl": "https://aisa.one/docs/api-reference",
"openApiUrl": "https://aisa.one/openapi.yaml"
},
"path": "/apis/v2/coingecko/simple/price",
"method": "GET",
"description": "Get cryptocurrency prices in multiple currencies",
"mimeType": "application/json",
"input": {
"type": "object",
"properties": { "ids": { "type": "string" } }
},
"output": { "type": "object" },
"siwx": false,
"supportsVanillax402": true,
"supportsCircleGateway": true
}
}
],
"pagination": { "limit": 50, "offset": 0, "total": 636 }
}
```
Each item in `items` describes one service:
* `accepts[]` lists the payment requirements the service accepts. Each entry
carries the `network` (CAIP-2), the `asset` (token contract address), the
`scheme` (for example, `exact`), the `amount`, and the `payTo` seller wallet.
`amount` is in atomic units: USDC has 6 decimals, so `10000` equals 0.01 USDC.
v2 uses `amount` (v1 used `maxAmountRequired`).
* `metadata.provider` describes the seller: `name`, `description`, `category`,
`tags`, `website`, and documentation URLs.
* `metadata` also carries the request `path` and `method`, an `input` and
`output` JSON Schema, and three capability flags: `supportsVanillax402`
(accepts onchain x402 payments), `supportsCircleGateway` (accepts Gateway
offchain batched payments), and `siwx` (requires browser-based Sign-In With
X).
## Examples
```bash Fuzzy search theme={null}
curl --compressed \
"https://api.circle.com/v2/x402/discovery/resources?query=weather"
```
```bash Filter by chain and price theme={null}
curl --compressed \
"https://api.circle.com/v2/x402/discovery/resources?network=eip155:8453&maxUsdPrice=0.01&siwx=false"
```
```bash Gateway-only on Base theme={null}
curl --compressed \
"https://api.circle.com/v2/x402/discovery/resources?supportsCircleGateway=true&network=eip155:8453"
```
```bash Circle CLI theme={null}
circle services search "weather"
```
## Categories
Every listing is classified with one category in `metadata.provider.category`.
Filter on it with the `category` query parameter to narrow results to a domain.
| Category | Description |
| :-------------------- | :------------------------------------------------------ |
| `SOCIAL_INTELLIGENCE` | Social platform data and audience or sentiment signals. |
| `FINANCIAL_ANALYSIS` | Market data, prices, and financial analytics. |
| `WEB_SEARCH_RESEARCH` | Web search, scraping, and research retrieval. |
| `PREDICTION_MARKETS` | Odds, forecasts, and prediction-market data. |
| `CREATIVE` | Media generation such as images, audio, and text. |
| `INFRASTRUCTURE` | Developer tooling and infrastructure utilities. |
## Paying for a service
Discovery tells you what each service accepts. To actually pay, use one of two
rails:
* **Vanilla x402**: a signed onchain USDC transfer that any USDC wallet,
including a centralized custodial one, can produce.
* **Circle Gateway**: offchain, batched settlement for gasless, sub-cent
payments.
Each listing's `accepts[]` and its `supportsVanillax402` and
`supportsCircleGateway` flags tell you which rails it takes. To pay from Circle
CLI, see
[Pay for a service](/agent-stack/agent-nanopayments/operations/pay-for-service).
For the concepts and buyer integration, see
[Agent nanopayments](/agent-stack/agent-nanopayments).
To find services payable on a specific blockchain, filter with the structured
`network` parameter, not the `query` text field. `query` matches free text
(URLs, providers, descriptions, tags), so it does not reliably match a chain.
## Related
* [Service catalog](https://agents.circle.com/services)
* [OpenAPI spec](https://agents.circle.com/.well-known/openapi.json)
* [A2A card](https://agents.circle.com/.well-known/a2a.json)
* [Agent skills index (llms.txt)](https://agents.circle.com/llms.txt)