Lenstrum

About & methodology

How Lenstrum analyses content

Framing & Perspectives

Text is extracted from the URL and passed to Claude with a structured non-partisan prompt. Results are rated Left, Centre, Right, or Unknown with a confidence level. Lenstrum analyses content, not source reputation.

AI involvement

The transcript is assessed for patterns associated with AI-generated text — unnatural fluency, absence of hesitation markers, and repetitive structure. Results are probabilistic indicators, not verdicts.

Source context

Lenstrum classifies the content type and provides a recommendation for how to contextualise the source. Related coverage from left, centre, and right outlets is surfaced using Brave Search.

Accuracy & Validation

90%

overall accuracy

100%

political YouTube

100

item validation corpus

Lenstrum's analysis engine has been validated against a 100-item corpus of political articles, political YouTube videos, non-political content, and balanced sources — tested against AllSides and Ad Fontes Media ratings. We publish our methodology openly because trust in a transparency tool has to be earned, not assumed.

Read the full methodology →

Our data sources

Claude (Anthropic) — performs bias, AI detection, and source context analysis via the Anthropic API.

Supadata — retrieves YouTube transcripts for video analysis.

Brave Search — surfaces related coverage from left, centre, and right outlets.

What we do not do

Lenstrum does not fact-check. A well-sourced, accurate article can carry an ideological lean — lean is a framing signal, not a quality judgment.

Lenstrum does not rate creators or outlets. It analyses specific pieces of content, not the broader output of a source.

Lenstrum cannot process content without available text. Videos without captions, paywalled articles with no excerpt, and private posts cannot be analysed.

The team

Lenstrum is an independent product. We publish our methodology openly and encourage users to challenge our outputs. If you spot a systematic issue with the analysis, use the feedback tools — they go directly to us.