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Home/Servers/VerifyAPI — Fact Check With Signed Receipts

VerifyAPI — Fact Check With Signed Receipts

by io.github.KyTheKitty

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

Power your agent

Add this server

The publisher's own command. Not a PlugMCP endpoint.

Local command
npx -y @verify-api/[email protected]
Credentials from the publisher
  • VERIFYAPI_API_KEY — Your VerifyAPI key (csk_live_...). Get one free at https://verify-api.dev/signup — no card required. Unset = free trial (3 calls per IP per 24h, cached tier, signed receipts still included).
  • VERIFYAPI_BASE_URL — Override the API base URL. Defaults to https://api.verify-api.dev.
Provider
Claude Code
VERIFYAPI_API_KEY=<secret> VERIFYAPI_BASE_URL=<value> claude mcp add io.github.kythekitty-verifyapi -- npx -y @verify-api/[email protected]

Run in a terminal.

Claude Desktop
{
  "mcpServers": {
    "io.github.kythekitty-verifyapi": {
      "command": "npx",
      "args": [
        "-y",
        "@verify-api/[email protected]"
      ],
      "env": {
        "VERIFYAPI_API_KEY": "<secret>",
        "VERIFYAPI_BASE_URL": "<value>"
      }
    }
  }
}

claude_desktop_config.json

Step-by-step: add this in Claude

Remote URL or a command on your machine? How the two installs differ

Run on PlugMCP

Host a copy with our keys and logs.

A new server you create. It is not this listing's official endpoint. Use the publisher install when you want their URL and their credentials.

Launch

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

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)

{
  "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:

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

Output:

{
  "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

VariableRequiredDefaultDescription
VERIFYAPI_API_KEYNo(unset = trial)Your VerifyAPI key (csk_live_...). Get one free at https://verify-api.dev/signup
VERIFYAPI_BASE_URLNohttps://api.verify-api.devOverride the API base URL. Useful for self-hosting or testing.

Programmatic API (skip MCP, call directly)

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.

Links

  • Website: https://verify-api.dev
  • API docs: https://verify-api.dev/docs
  • Signup (free, no card): https://verify-api.dev/signup
  • npm: https://www.npmjs.com/package/@verify-api/mcp
  • MCP Registry: https://registry.modelcontextprotocol.io/v0/servers/io.github.KyTheKitty/verifyapi
  • MCP source: https://github.com/KyTheKitty/verifyapi-mcp
  • Backend source (Fastify service, Terraform, receipts pipeline): https://github.com/KyTheKitty/verifyapi

Built by

Circuit Savers LLC — Wausau, Wisconsin.

License

MIT

How do I install VerifyAPI — Fact Check With Signed Receipts?
Copy the stdio config for Cursor, Claude Desktop, Claude Code, or VS Code on this page. It uses the publisher's install, not a PlugMCP proxy.
Does VerifyAPI — Fact Check With Signed Receipts need an API key?
The publisher lists these environment variables: VERIFYAPI_API_KEY, VERIFYAPI_BASE_URL.
What transport does VerifyAPI — Fact Check With Signed Receipts use?
VerifyAPI — Fact Check With Signed Receipts runs locally over stdio.
When was VerifyAPI — Fact Check With Signed Receipts last checked?
Last checked 2026-10-16. Fact-check any claim with live web sources. Ed25519-signed receipts. Catches hallucinations.

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