Understand every flag
See the exact wording or punctuation that triggered a rule, why it matters, and where it appears in the document.
Sentence rhythm
Working…
Reddline
Reddline is a free, open-source AI writing pattern detector and style editor. It scans punctuation, phrasing, openings, closings and sentence rhythm that can make prose read as machine-written, then explains each flag so you can decide what to change.
Drop a manuscript on the desk
Paste text, or import a Word doc, PDF, or plain text file.
Reddline marks the habits that make writing read as machine-made.
Or click the page and start typing. ⌘V works anywhere.
How Reddline helps your writing
Use deterministic scanner rules for a private first pass, review every finding in context, and add AI assistance only when you choose.
Preserve your voice
Create separate voice profiles from your own samples and compare rhythm, vocabulary, formality and other style signals.
Stay in control
Revise by hand, apply a focused automatic fix, or use your own Claude, ChatGPT or Gemini API key for contextual editing.
Is Reddline an AI detector?
Reddline identifies patterns often associated with machine-written prose. It does not calculate an authorship probability and cannot prove whether a person or an AI wrote a passage. Its purpose is to improve the writing, not judge its origin.
Does Reddline keep writing private?
Rules only analyses document and voice text in this browser. Rules + AI sends relevant document text, voice statistics and short sample excerpts to the provider you select only when you invoke an AI feature. Documents and voice samples are stored locally in browser storage.
What files can Reddline use?
Reddline imports Word, PDF, Markdown and plain-text files. Clean text can be copied or exported, and Word exports can include tracked changes and review comments.
Open source under AGPL-3.0. View the source on GitHub. Built by Pract.ai.