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Cited Brief
x402
Cited Brief is a paid API for AI agents from cited-brief.cited-brief.workers.dev, paid per call via x402, $0.1/call, status unknown (last checked 2026-10-13).
Answers a user question by extracting and citing evidence from specified web pages, returning a verified answer with source quotes
Price / call$0.1
Success—
StatusUnknown
How this service works
Pay-per-call web research tools for AI agents, paid in USDC over x402.
Output
A JSON object containing a plain-language answer to the question, an array of claims each with the source URL, the verbatim quote used, and the supporting text, plus a count of claims dropped for being unverifiable and the model that generated the answer.
Example use cases
Competitive pricing research from live pages
“Look at https://notion.so/pricing and https://www.notion.so/help/billing and tell me: what does the Plus plan cost per user per month when billed annually?”
Policy detail lookup from company docs
“Check https://openai.com/policies/usage-policies and answer: what types of content are explicitly prohibited under OpenAI's usage policy?”
Feature verification before recommending a tool
“Read https://linear.app/features and https://linear.app/changelog and answer: does Linear support GitHub integration, and if so what does it do?”
Technical details
Endpoint
POSThttps://cited-brief.cited-brief.workers.dev/brief?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need a grounded, citation-backed answer derived from specific known URLs rather than a broad web search. It is ideal when you already know which pages contain the answer and want verifiable quotes — not open-ended discovery. Prefer it over general search APIs when auditability and source traceability matter, and over raw scraping when you need a synthesized answer rather than raw HTML. The pay-per-call USDC model makes it suitable for on-demand agent workflows without subscriptions.
Side effects
- URL is behind a paywall or login — page content cannot be fetched, claim dropped
- URL returns non-HTML content (PDF, binary) — may fail to extract text
- Question exceeds 500 characters — request rejected with validation error
- Fewer than 1 or more than 5 URLs provided — request rejected
- No verifiable evidence found in pages — answer returned with zero claims
- Page loads slowly or times out — dropped from evidence set
- USDC payment insufficient or x402 handshake fails — payment error, call not executed
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| urls | array | Public http(s) pages to answer from |
| question | string | The question to answer |
Output
Schema · Response
{
"type": "json",
"example": {
"model": "gemini-3.5-flash-lite",
"answer": "The Pro plan costs $10 per user per month when billed yearly.",
"claims": [
{
"url": "https://example.com/pricing",
"text": "Pro is $10 per user per month, billed yearly",
"quote": "Pro $10 per user/month billed annually"
}
],
"question": "What does the Pro plan cost per user per month, billed yearly?",
"dropped_unverified": 0
}
}Tags
x402
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