VerifyAPI — fact-check with signed receipts

Name: VerifyAPI — fact-check with signed receipts
Author: kythekitty

@kythekittyMCP server · External

Fact-check any claim with live web sources. Ed25519-signed receipts. Catches hallucinations.

Fact-checkingv0.1.9TypeScript

Freeno charge per call

How to install

Runs on your machine from its package; the steps are below.

What it does

Reads
Writes
High impact

At most: only reads or looks up information.

What it costs

Free

Odel charges nothing per call. The publisher may charge for its own service.

Runs locally over stdio

This server isn't hosted — your MCP client launches it from a package registry. Use one of the commands below, or drop the config into your client (e.g. Claude Desktop).

npm@verify-api/mcpv0.1.9

Run

npx -y @verify-api/mcp

MCP client config

{
  "mcpServers": {
    "verifyapi-fact-check-with-signed-receipts": {
      "command": "npx",
      "args": [
        "-y",
        "@verify-api/mcp"
      ]
    }
  }
}

README3 min readView on GitHub

VerifyAPI MCP Server

Fact-check any claim before you act on it. One tool. Live web sources. Cryptographically signed receipts.

What it does: VerifyAPI is a Model Context Protocol server that verifies factual claims against live web sources and returns a citable verdict — including the source URL, published date, a verbatim quote, and an Ed25519-signed receipt so downstream systems can prove the check actually happened.

When to use it: Any time your agent is about to act on a factual claim it can't cite. Prices, dates, versions, quotes, statistics, product specs, event outcomes. If getting it wrong would cost time, money, or trust — verify first.

Quick install (Claude Desktop / Cursor / Cline / any MCP client)

json

{
  "mcpServers": {
    "verifyapi": {
      "command": "npx",
      "args": ["-y", "@verify-api/mcp@latest"],
      "env": {
        "VERIFYAPI_API_KEY": "csk_live_..."
      }
    }
  }
}

No API key? Leave VERIFYAPI_API_KEY unset for the free trial (limited to 3 calls per IP per 24h, signed receipts included). Get a free key at https://verify-api.dev/signup — no credit card required.

The one tool: `verify_claim`

Input:

json

{
  "claim": "Python 3.13 was released in October 2024."
}

Output:

json

{
  "verdict": "supported",
  "confidence": 0.99,
  "source_url": "https://docs.python.org/3/whatsnew/3.13.html",
  "exact_quote": "Python 3.13 was released on October 7, 2024.",
  "reasoning": "Multiple authoritative sources confirm...",
  "receipt": {
    "jws": "eyJhbGci...",
    "kid": "pQAd73zRp9Xq9Y5U"
  }
}

Verdicts: supported, contradicted, unverifiable. Every supported/contradicted verdict comes with a JWS receipt signed by keys served at https://api.verify-api.dev/.well-known/jwks.json.

Why signed receipts?

Because "the AI checked" is not the same as "the AI verified." A signed receipt lets a downstream system — compliance auditor, user, another agent, a smart contract — cryptographically prove that a specific claim was verified against a specific source at a specific time by VerifyAPI's known public key. It's the difference between saying "trust me" and handing over a notarized document.

Pricing

Free trial: no signup, no card. Limited to 3 calls per IP per 24h. Includes signed receipts.
With API key: $0.02 per verified claim. Unverifiable / out-of-scope calls are free (you don't pay for "I couldn't find enough evidence").
Freshness tiers: standard verification $0.02, real-time (fresh-fetch) $0.05.
Auto top-up: save a card, set a threshold, keep flowing. POST /v1/balance/autorefill.

Example use cases

LangChain / LlamaIndex agents: wrap verify_claim as a Tool. Have your agent call it before returning any factual answer.

Cursor / Cline coding agents: verify version numbers, API existence, deprecation status before writing imports.

Claude Desktop workflows: "Verify this quote is real before I put it in the deck."

Multi-agent systems: pass receipts between agents to prove groundedness up the chain.

Compliance-sensitive automation: keep the JWS receipts as audit trail for every factual decision the agent made.

Environment variables

Variable	Required	Default	Description
`VERIFYAPI_API_KEY`	No	(unset = trial)	Your VerifyAPI key (`csk_live_...`). Get one free at https://verify-api.dev/signup
`VERIFYAPI_BASE_URL`	No	`https://api.verify-api.dev`	Override the API base URL. Useful for self-hosting or testing.

Programmatic API (skip MCP, call directly)

bash

curl -X POST https://api.verify-api.dev/v1/verify \
  -H "Authorization: Bearer csk_live_..." \
  -H "Content-Type: application/json" \
  -d '{"claim": "Bitcoin ETFs were approved by the SEC in January 2024."}'

Full OpenAPI spec: https://api.verify-api.dev/openapi.json

x402 payment support built in — see https://verify-api.dev/agents.txt for the agent-native discovery manifest.