---
title: "Paid: Real-time fact check with sourced verdict"
method: POST
path: "/api/x402/fact-check"
---

# Paid: Real-time fact check with sourced verdict

`POST /api/x402/fact-check`

## Request

- Base URL: `https://three.ws`
- URL: `https://three.ws/api/x402/fact-check`
- Auth: none required

Pay $0.10 USDC to verify a factual claim. The server generates search queries, runs multi-source web search, extracts per-source stance with an LLM, computes a weighted verdict + confidence, and returns the supporting sources plus a SHA-256 attestation of the result.

## Request body

- object
  - `claim` string, required: The factual claim to verify.
  - `strictness` 'high' | 'medium' | 'low': high: penalizes low-authority sources. medium: default. low: accepts all sources equally.

## Response `200`

Verdict JSON: verdict, confidence, claim, strictness, sources, costBreakdown, attestation

## Other responses

- `400`: Missing or invalid claim
- `402`: Payment Required (x402)

---

[API](https://skmtc.dev/three/apis/three-ws-api.md) · [All operations](https://skmtc.dev/three/apis/three-ws-api/llms.txt) · [OpenAPI document](https://skmtc.dev/three/apis/three-ws-api/revisions/dbc5e3a81b79?raw)