n8n-nodes-lenz

This is an n8n community node. It lets you use Lenz in your n8n workflows.

Lenz is an audit-grade AI fact-checking API. It catches hallucinations and gives sourced, branch-ready verdicts on any claim or piece of text — not just a bare confidence score.

n8n is a fair-code licensed workflow automation platform.

Installation Operations Credentials Compatibility Usage Example workflow Resources Version history

Installation

Follow the installation guide in the n8n community nodes documentation, and search for n8n-nodes-lenz under Settings → Community Nodes → Install.

Operations

| Operation | What it does | |---|---| | Verify (Deep) (default) | Full 8-model pipeline (research → debate → adjudication), ~90 seconds. Returns a verdict, confidence, lenz_score (1-10), sourced citations, and an executive summary. Reserve for high-stakes claims that need a thorough, cited answer. | | Assess (Fast) | A quick 3-model panel verdict, ~5-10 seconds, one entry per claim identified in the input text. Good default for lower-stakes checks. | | Extract Claims | Free — pulls the verifiable factual claims out of a block of text without checking them. Useful as a first step before running Assess or Verify on each claim individually. | | Ask Follow-Up | Asks a question grounded in the full research behind a completed Verify (Deep) result. Requires the verification_id that Verify returns — not usable standalone. | | Check Usage | Returns remaining quota per capability (assess / verify / ask), current plan, and when quota resets. |

Every claim-checking operation returns a branch-ready passed boolean (derived from the verdict) alongside the raw verdict/confidence/citations, so you can wire an IF node directly off the result — e.g. route failed claims to human review.

Credentials

You'll need a free Lenz API key:

1. Sign up at lenz.io/api-integration to get a key (starts with lenz_).
2. In n8n, add new credentials of type Lenz API, paste the key, and click Test to confirm it's valid.

Compatibility

Built against n8n-workflow (n8n API version 1) and tested against n8n v2.29.x. No known version incompatibilities.

Usage

• Verify (Deep) takes ~90 seconds — it's the full multi-model pipeline, not an instant call. The node blocks/polls until the result is ready, so no separate polling setup is needed on your end.
• To feed data from a previous node instead of a fixed value, toggle a field to Expression and reference it, e.g. {{ $json.output }}.
• For Ask Follow-Up, keep the Question field as a fixed, generic string (e.g. "What are the main sources supporting this verdict?") and only make the Verification ID dynamic via expression — that way the same follow-up question works for whatever claim was just verified.
• The node is usableAsTool, so it can also be called directly by an n8n AI Agent as a tool, not just as a manual workflow step.

New to n8n? See the Try it out documentation to get started with the basics first.

Example workflow

A simple "fact-check gate" pattern — verify an LLM's output before acting on it:

[LLM node]  ──▶  [Lenz node]  ──▶  [IF node]  ──┬─▶ (true)  continue normally
 generates          Operation:        checks         └─▶ (false) route to human review
 an answer          Verify (Deep)     {{ $json.passed }}
                     Claim: {{ $json.text }}

1. Add an LLM node (or any node producing text) upstream.
2. Add the Lenz node, set Operation to Verify (Deep), and set the Claim field to an expression referencing the upstream output, e.g. {{ $json.text }}.
3. Add an IF node after Lenz with the condition {{ $json.passed }} is true.
4. Wire the true branch to continue the workflow normally, and the false branch to whatever your "needs review" path is (Slack alert, email, a manual-approval step, etc.).

For a lighter check on lower-stakes content, swap the Lenz operation to Assess (Fast) instead — same wiring, ~5-10s instead of ~90s.

Follow-up questions on a completed verification

Ask a grounded question about the evidence behind a Verify (Deep) result, by chaining two Lenz nodes:

[Lenz node]  ──▶  [Lenz node]
 Operation:          Operation:
 Verify (Deep)       Ask Follow-Up
                     Verification ID: {{ $json.verification_id }}
                     Question: "What are the main sources supporting this verdict?"

1. Add a Lenz node, set Operation to Verify (Deep), and run it.
2. Add a second Lenz node after it, with Operation set to Ask Follow-Up.
3. Set the Verification ID field to an expression referencing the first node's output: {{ $json.verification_id }}.
4. Keep the Question field as a fixed string (e.g. "What are the main sources supporting this verdict?") — it works for whatever claim was just verified, since only the Verification ID needs to change per run.

Resources

• n8n community nodes documentation
• Lenz API documentation
• lenz-io Node SDK (a standalone SDK for the same Lenz API, if you're building outside n8n)

Version history

• 0.1.0 — Initial release. Verify (Deep), Assess (Fast), Extract Claims, Ask Follow-Up, and Check Usage operations; API-key credential with live test endpoint.
• 0.1.1 - 0.1.3 — Publishing pipeline fixes (GitHub Actions provenance, npm trusted publishing).
• 0.1.4 — Bundled lenz-io at build time (zero runtime dependencies, required for n8n Cloud verification); added a Jest test suite; fixed an error-message bug in the NodeApiError wrapping; replaced the placeholder icon with the real Lenz brand mark.
• 0.1.5 — Corrected the maintainer email in package.json to match the npm account.
• 0.1.6 — Fixed every violation found by n8n's official @n8n/scan-community-package compliance scanner: test files no longer ship in the package; the bundled lenz-io SDK is properly tree-shaken (dropping unused webhook-signature-verification code); replaced remaining restricted-global usage (setTimeout, process, console, globalThis) with scanner-safe equivalents; and stopped emitting unused .d.ts declaration files. Also fixed a dormant bug in the npm publish workflow.
• 0.1.7 — Clarified the Verification ID field description and added an Ask Follow-Up wiring example to the README.
• 0.1.8 — Rewrote the node to call the Lenz REST API directly via n8n's httpRequestWithAuthentication helper, removing the lenz-io SDK dependency entirely (zero runtime dependencies, no build-time bundling). This resolves the source-level restricted-import violations required for n8n Cloud verification.