For teams shipping AI-drafted text

Fact-check the draft before it goes out.

Lenz is a fact-checking service for newsletters, briefs and posts. It identifies factual statements it can check against independent public sources and returns a result for each.

€10,000 warranty per qualifying fact check

Fact-check AI-generated newsletters, briefs, posts and reports before publishing.

  1. The draft is ready

    An issue, a brief, a post, a report — whether a model wrote the first pass or you did.

  2. Lenz finds the checkable statements

    You hand over the whole piece rather than a list. Lenz picks out the factual statements it can check against independent public sources and leaves the opinions and the recommendations alone.

  3. Each one comes back with a result

    An assessment returns a verdict and a confidence level per statement in about 10 seconds; that is how you sort a whole issue. Send the ones that matter to a full verification, where the verdict comes from sources Lenz went and found.

  4. You decide what to publish

    Read the results before the issue goes out: cut a line, fix a figure, or run a full verification on the one you are least sure of. The editorial call is yours.

  5. Publish, with the checks behind it

    Each full verification keeps a record you can reopen: the statement as framed, the verdict and score, every source with its date, the reasoning. A figure questioned later has a check behind it.

Try it on your own draft →

Market briefs, news digests and articles

Paste the whole piece. Lenz returns a result per statement, not one verdict for the document, so a wrong figure is named with its own sources.

Blog posts, press releases and social media posts: the statistics in them

A statistic is checked like any other statement: Lenz looks for where the number was published and reports what it found, including when that is nothing.

Check ChatGPT-drafted content and X or LinkedIn posts inside Claude or Cursor.

Connect Lenz to Claude with one sign-in, no key; Cursor and Claude Code take one command with your key. Paste the post or the draft and ask for a check; the results come back in the same window.

Connect Claude →

Automate checks on recurring LLM output: briefs, digests, documents.

For a daily brief or a batch of model-drafted documents, a short Python script: extract the statements, assess them together, route False, Mixed and low-confidence results to your reviewer. The routing is your policy.

Python pip install lenz-io

# a recurring draft: extract the statements, assess them together, route the flagged ones
from lenz_io import Lenz

client = Lenz(api_key="lenz_...")
extracted = client.extract(text=draft)
# identified_claims is empty when the text yields a single statement
claims = extracted.identified_claims or [extracted.claim]
r = client.assess(claims=claims)   # one row per statement, same order

# your routing policy. "Error" means the item was not checked — never read it as clean
flagged = [c for c in r.claims
           if c.verdict in ("False", "Mostly False", "Mixed", "Error")
           or c.confidence == "low"]

send_to_reviewer(draft, flagged)   # your own function: an email, a ticket, a Slack message

The full sequence is extract → assess → verify → ask. Pipelines, webhooks and the TypeScript SDK are on the developer page.

A scheduled digest or a batch of documents runs unattended: Lenz posts each result back when it lands, so nothing polls, and a retried request never runs the same check twice.

What a full verification looks like.

A full verification is the investigation, not a longer assessment. Lenz searches independent public sources for the statement, has models argue both sides on what it found and a panel review the arguments, then returns the verdict with those sources and the reasoning. About 90 seconds per statement.

Warranty

Vendors disclaim accuracy. Lenz warrants the verdict.

A verdict can qualify when a full verification returns True or False with high panel confidence and enough independent sources behind it.

On a paid Developer or Scale plan, every full verification that qualifies carries a contractual warranty, at no extra charge.

How the warranty works →

Pricing: start free, no card.

Free tier, no card: 100 assessments or 10 full verifications a month, in any combination. The Developer tier is $99 a month for 5,000 assessments or 500 full verifications, the same way, and the Scale tier is $399 a month for production volumes. Every plan includes 1,000 extractions a day, an extraction being one call however long the text.

Compare plans →

Frequently asked questions

No. Connecting Lenz to Claude is one sign-in and needs no key. Cursor and Claude Code take one command with your key. You can also use a script to automate checks.

Two different checks. An assessment is a judgement: a panel of models reads the statement and returns a result and a confidence level in about 10 seconds. A full verification is an investigation: Lenz searches independent public sources and returns the verdict with those sources and the reasoning, in about 90 seconds per statement.

Nothing is invented to fill the gap. When Lenz finds no public evidence for a statement, the finding says so and the result scores low. Treat that statement as unverified.

Submissions through the API and the connectors are private to your account.

Check the next issue, statement by statement.