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x402 Agent Services – Web Answer (AI-powered Q&A)
x402
x402 Agent Services – Web Answer (AI-powered Q&A) is a paid API for AI agents from call402.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-19).
Answers a natural-language question with a cited AI-generated response, sourced from live web content via Exa, billed at $0.02 USDC per call via the x402 micropayment protocol on Base mainnet.
Price / call$0.02
Success—
StatusUnknown
How this service works
USDC pay-per-call APIs for AI agents via the x402 protocol (v2, exact, Base mainnet). Send a request, receive HTTP 402 with payment requirements, pay with @x402/fetch or any x402 client, retry with the PAYMENT-SIGNATURE header.
Output
Returns a JSON object containing an AI-generated answer string, the original query, citation count, and an array of citations each with URL, title, optional author, and published date. The meta object includes the source identifier ('exa-answer') and a request_id.
Example use cases
Real-time crypto price lookup
“What is the current price of ETH and where is that data coming from?”
Breaking news fact check
“What happened with the SEC and Ethereum ETFs this week? Give me a short answer with sources.”
Live regulatory research
“What are the current capital gains tax rates for crypto in the US? I need a sourced answer.”
Technical details
Endpoint
POSThttps://call402.com/api/web-answer?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need a cited, real-time answer to a factual or current-events question and you are operating in an x402-capable agent environment with a USDC wallet on Base mainnet. It is especially useful when freshness matters (prices, news, regulations) and you need traceable sources rather than a hallucinated answer. Prefer alternatives if you need bulk queries, streaming responses, or cannot execute micropayments programmatically.
Side effects
- HTTP 402 returned before payment — agent must pay with PAYMENT-SIGNATURE header and retry
- Insufficient USDC balance on Base mainnet causes payment failure
- Malformed or missing 'query' field returns a 400-level error
- Query yields no matching web sources, resulting in an empty or low-confidence answer
- Network timeout if the Exa backend is slow to respond
- Invalid x402 client version incompatible with v2/exact payment scheme
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| query | string | Natural-language question |
Output
Schema · Response
{
"type": "json",
"example": {
"meta": {
"source": "exa-answer",
"request_id": null,
"citations_count": 1
},
"query": "What is the current price of ETH?",
"answer": "ETH is trading at about $4,100.",
"citations": [
{
"url": "https://example.com",
"title": "Example source",
"author": null,
"published_date": "2026-10-01"
}
]
}
}Tags
x402
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