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Building with AI?
Catch factual errors before they ship.

An independent, multi-model fact-checking API for the teams that can’t afford to ship a wrong claim.

Multiple models across five stages, grounded in independent sources. Opposing-side debate, three independent reviewers, full citation trail.

PH exclusivePro access

The Product Hunt offer

This offer has ended

Lenz is still free to try. Create an account or see the plans for Pro access.

/extract1,000 / day /assess5,000 / mo /verify500 / mo /ask5,000 / mo /reviewfrom the same credits
Integrates with Zapier n8n Claude ChatGPT MCP REST API Python SDK TypeScript SDK

How it works

Multiple models. Five stages. One auditable verdict.

01 — Submit

Send a claim to the API

Lenz frames it as a precise, falsifiable statement — removing ambiguity before research begins.

Framing
02 — Research & Debate

Lenz searches, then argues both sides

Multiple queries across authoritative sources. Two models argue opposing sides from the evidence — disagreement is preserved, not averaged away.

Research→ Debate→ Panel Review
03 — Verdict

Structured output — block, publish, or escalate

A score, sourced citations, and a full reasoning trace. Machine-readable so your workflow branches automatically.

Conclusion

API surface

Pro tier — API surface.

EndpointWhat it doesQuota
/extract Pull verifiable claims from any text 1,000 / day
/assess Inline guardrail before output reaches users 5,000 / mo
/verify Full multi-model pipeline — framing to sourced verdict 500 / mo
/ask Ask a factual question, get a sourced answer 5,000 / mo
/review Whole-draft review — issues in claims and citations from the same credits

Use cases

Where teams are integrating Lenz.

  • AI content before publishing

    Newsletters, blog posts, product updates — claims verified before they reach subscribers or go live.

    AI Draft→Lenz→PublishHold

  • Data enrichment & CRM

    LLMs routinely invent funding rounds, headcounts, and tech stacks. Verify enriched records before they enter your CRM.

    Enriched Record→Lenz→ImportFlag

  • Regulated claims

    Health, finance, and supplement copy where the audit trail is the deliverable — not an optional extra. Highest stakes, full trace.

    Copy Draft→Lenz→ApproveBlock

  • Agent guardrail

    Wire /assess as a ~15 s pre-action check before your agent acts on a factual claim. Full verify only when the stakes warrant it.

    Agent Claim→Lenz→ProceedPause

  • Customer support AI

    Catch a wrong answer before it reaches the customer — verified at the point of response, not after the complaint arrives.

    AI Response→Lenz→SendEscalate

  • RAG response gating

    Groundedness checks verify retrieval faithfulness — not whether the source itself is wrong. Lenz checks the claim against the open web.

    RAG Output→Lenz→ReturnReview
63%

of real-world fact-checks return a dissenting verdict across five frontier LLMs. The choice of model is an invisible editorial decision — Lenz returns a verdict grounded in independent sources, not model consensus.

Read the research

This offer has ended.

Lenz is still free to try — multiple models across five stages, with the full trace on every verdict.

Create an account → See how the pipeline works Contact us