x402 API Access
AgentIndex search endpoints are available via x402 micropayments on a dedicated subdomain. Each request costs 0.02 USDC on Base. No API keys, no subscriptions — pay per request with on-chain settlement.
Price Per Request
$0.02
USDC on Base
Network
Base
eip155:8453
Protected Endpoints
3
Base URLhttps://x402.agentindex.space
Protected Endpoints
Method | Path | Description | Price |
|---|---|---|---|
GET | /v1/search | Global search across agents, addresses, tags, and endpoints | 0.02 USDC |
GET | /v1/search/agents | Agent metadata search by name, tags, or services | 0.02 USDC |
GET | /v1/agents | Agent directory listing with filtering and pagination | 0.02 USDC |
Free Endpoints — The following endpoints are not paywalled and remain accessible on the main API:
GET /v1/agents/:agentId— Individual agent lookupGET /v1/health— Health check
How x402 Works
1. Request
Client sends a normal GET request to
x402.agentindex.space. 2. Challenge
Server responds with HTTP
402 Payment Required and includes payment details (network, token, amount, recipient) in headers. 3. Pay
Client submits a 0.02 USDC payment on Base (eip155:8453) to the specified recipient address.
4. Retry with proof
Client retries the original request, attaching the x402 payment proof in the request header.
5. Response
Server validates the payment proof and returns the requested data.
Integration Example
Send a request without payment to see the 402 challenge:
Request
curl -i "https://x402.agentindex.space/v1/search?q=chatbot"
Expected 402 response:
Response
HTTP/1.1 402 Payment Required
X-Payment-Network: eip155:8453
X-Payment-Token: USDC
X-Payment-Amount: 0.02
X-Payment-Recipient: 0x...
Content-Type: application/json
{
"error": "Payment Required",
"accepts": {
"network": "eip155:8453",
"amount": "0.02",
"asset": "USDC"
}
}