Claim framing
Lenz converts a claim into a precise, testable statement before research begins, which helps reduce ambiguity and makes downstream verification more consistent.
Lenz
Lenz is a fact-checking API for verifying AI-generated or manual claims before publication, with cited, auditable verdicts and API, SDK, CLI, MCP, n8n, and Zapier integrations.
Overview
Lenz is a fact-checking API and toolset for AI-generated content and other claims that need verification before they are published or acted on. The product is built to sit inside workflows, where it can screen output from AI systems, verify facts in drafts, or answer a factual question with cited evidence.
Its verification process is structured and auditable: a claim is framed, researched across independent sources, debated from both sides, reviewed by multiple models, and then returned as a verdict with citations and a reasoning trace. The site also presents Lenz as a drop-in layer for teams that want to block, publish, or escalate claims based on structured output rather than a manual review step.
Core features
Multi-source research
The product searches multiple independent sources and reads the source pages themselves, extracting quotes and scoring evidence for authority, relevance, and recency.
Opposing-side debate
Two models debate opposite positions, then rebut each other using only collected evidence, so disagreement is preserved instead of collapsed into a single average answer.
Panel review
Three additional models review source reliability, logical support, and whether the wording and numbers match the evidence, adding a separate review layer before conclusion.
Auditable verdicts
Verification returns a structured result with a truth classification, Lenz Score, citations, and a reasoning trace that can be audited or used in automated workflow branches.
Multiple integration surfaces
The same core primitives are exposed through the API, SDKs, CLI, MCP, n8n, and Zapier, so the same verification logic can be used in different tools.
Where Lenz fits
Content publishing review
Use Lenz to check newsletter, blog, or product-update copy before it reaches subscribers or goes live, especially when a draft contains claims that need sourcing.
Data enrichment validation
Verify enriched fields such as funding rounds, headcount, or tech stack data before importing records into a CRM or dataset.
Regulated claims review
Screen health, finance, or supplement copy where the full audit trail matters and a simple yes/no answer is not enough.
Agent guardrails
Add /assess as a pre-action check in agent workflows so the system can pause or continue based on whether a factual claim passes verification.
Interactive fact-checking
Use the /ask flow or an assistant integration to answer a factual question with grounded sources while working in tools like Claude, Cursor, or ChatGPT.
Pros and Cons
Pros
- Provides a clear, multi-stage verification workflow rather than a single opaque score.
- Returns citations and a reasoning trace, which supports auditability.
- Offers several integration paths, including API, SDKs, CLI, MCP, n8n, and Zapier.
- Covers both standalone fact-checking and workflow gating for AI-generated output.
- Plans are self-serve, and the site says no card is required to start on the free plan.
Cons
- The free plan is limited, and higher-volume usage requires a paid plan.
- The site emphasizes a multi-stage AI pipeline, which may be more than some simple fact-checking tasks need.
- The public pages provide limited detail on exact limits and implementation specifics for every integration.
FAQ
What does Lenz verify?
Lenz is designed as a fact-checking layer for AI pipelines. It can be used on claims generated by a product, or on a claim a person types in manually, and returns a sourced verdict with citations.
How can Lenz be integrated into a workflow?
The site describes four API primitives: /extract, /assess, /verify, and /ask. The product also offers integrations through n8n, Zapier, MCP, CLI, and typed Python and TypeScript SDKs.
What does the verification output include?
The verification flow shown on the site has five stages: framing, research, debate, panel review, and conclusion. The output includes a truthfulness label, a Lenz Score, citations, and reasoning trace.
Is there a free plan or trial?
The plans page shows a Free plan, plus Plus, Developer, Scale, and Enterprise options. Paid plans are self-serve and can be canceled any time, and the site says no card is required to start on the free plan.
Who is Lenz for?
Lenz is positioned for teams that want to prevent unsupported claims from shipping, including content publishing, data enrichment, customer support, regulated claims, and agent guardrails.
Quick Facts
- Category
- Developer Tool
- Product type
- Fact-checking API and workflow tool
- Primary use
- Verify claims before publishing or taking action
- Integrations
- n8n, Zapier, Claude Desktop, Cursor, ChatGPT, CLI, REST API, Python SDK, TypeScript SDK, MCP
- Pricing
- Free plan available; paid plans include Plus, Developer, and Scale
- Website
- lenz.io
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