Lexicon: Free Writing App & Offline Grammarly Alternative

Lexicon is a free, open-source, local-first writing app for Windows, macOS, and Linux with offline grammar checking, local AI rewrites, and clean PDF export. No accounts required.

Key Features

• Write Editor: A calm canvas for first drafts with headings, lists, tasks, tables, and images, plus slash commands and local auto-save.
• Deep Proofread: Pairs LanguageTool's deterministic grammar rules with Lex's local LLM clarity in a dual-layer architecture.
• Local AI Rewrites: Run a built-in model (~5 GB) on supported builds, or connect your own Ollama or LM Studio server.
• Browser Extension (beta): For Chrome and Firefox, proofreads multiple visible text fields, including supported frames, through the desktop app.
• Deep Shadow DOM & Rich Editors: Accurately traverses complex web editors and nested shadow roots without trapping keyboard focus, with instant offline status alerts.

Privacy

and Local-First Lexicon emphasizes local-first operation, with built-in proofreading and local AI running on your machine. No accounts, reducing reliance on cloud services.

Platforms

and Availability Supports Windows, macOS, Linux, and Web. Offers free and freemium models.

Caveats

Google Docs is not supported yet, the Firefox package is unsigned (temporary install only), and the desktop app must be running.