Research Tool

Lenz

AI fact-checking API — verify claims with citations from multiple models and a full audit trail

lenz.io

Verified API available Works with n8n Free tier

Quick facts
What is it	AI fact-checking API — verify claims with citations from multiple models and a full audit trail
Pricing	Freemium — from $7.99/mo
Free tier	Yes
Platform	API
API	Yes
Works with	n8n
Best for	incident triage for AI-generated content, pre-release CI verification of AI outputs
Domain registered	2022

Data updated Aug. 1, 2026

What does Lenz do?

Lenz is an audit-grade AI fact-checking API. It lets developers add a verification layer to their AI products. You send a claim, and Lenz returns a verdict with citations from real sources. The system uses eight models across five stages, including opposing-side debate and three independent reviewers. The goal is to reduce hallucinations in AI-generated content by providing a transparent, sourced result.

How it works: Lenz offers four API primitives. /extract pulls verifiable claims from any text. /assess gives a fast multi-model verdict for synchronous user experiences. /verify runs the full adversarial pipeline with citations. /ask allows follow-up questions grounded on a previous verification. The pipeline pulls from multiple LLM vendors to cross-check claims, then simulates a debate between opposing sides and has three reviewers sign off. The output includes a full citation trail, so you can trace every fact back to its source. This is more thorough than a single-model fact-check.

Who benefits: AI product teams can use Lenz for incident triage, pre-release CI, and runtime verification. Developers building chatbots, assistants, or content generators can add a fact-checking layer without building their own pipeline. Researchers and fact-checkers can also use the web interface to verify single claims. The tool is designed for situations where accuracy matters and hallucinations are costly.

Research Tool

Key features

What makes it stand out

Extract verifiable claims from any text with the /extract endpoint

Get a fast multi-model verdict for synchronous user experiences with /assess

Run a full adversarial pipeline with cited sources and opposing-side debate via /verify

Ask follow-up questions grounded on a previous verification with /ask

Achieve audit-grade accuracy with eight models, three independent reviewers, and a full citation trail

Who is Lenz for?

Who benefits most from this tool

incident triage for AI-generated content

pre-release CI verification of AI outputs

real-time fact-checking in chatbots and assistants

Pricing

Free tier available — start without a credit card

Free

1,000 extractions/day /extract
100 fast checks/mo /assess
10 deep verifications/mo /verify
20 follow-ups/mo /ask
API + Python & TypeScript SDKs + CLI

Plus

$7.99/month

Everything in Free, plus:

500 fast checks/mo /assess
50 deep verifications/mo /verify
100 follow-ups/mo /ask
Cancel any time

Developer

$99.0/month

Everything in Plus, plus:

5,000 fast checks/mo /assess
500 deep verifications/mo /verify
1,000 follow-ups/mo /ask
Cancel any time

Scale

$399.0/month

Everything in Developer, plus:

20,000 fast checks/mo /assess
2,000 deep verifications/mo /verify
4,000 follow-ups/mo /ask
Cancel any time

Trust & presence

Domain Domain registered 2022

Gallery

Click any image to enlarge

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