The full upstream README, mirrored here for reference. Install config, tool schemas, adoption signals, and an original overview live on the VerifyAPI — fact Check with signed receipts listing page.
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.
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.
verify_claimInput:
Output:
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.
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.
POST /v1/balance/autorefill.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.
| 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. |
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.
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MIT