LanguageTool is an open-source AI-powered grammar, style, spelling, and punctuation checker supporting over 30 languages, ideal for writers, students, professionals, and non-native speakers seeking polished text.

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🚀 Overview

LanguageTool is a versatile, open-source proofreading tool that detects and corrects errors in grammar, spelling, style, punctuation, and casing across more than 30 languages and dialects, using both traditional rules and neural network-based AI for advanced suggestions like paraphrasing.

It solves the common problem of writing imperfections that undermine clarity and professionalism in emails, documents, essays, blog posts, and social media, providing instant feedback to improve text quality. It's built for individuals, students, businesses, and organizations—trusted by over 2,000 entities like BMW Group and the European Union—who need reliable multilingual writing assistance.

The project originated as an open-source initiative by Daniel Naber and a community of 200+ contributors to offer a free, customizable alternative to proprietary grammar tools, evolving into a full ecosystem with free basic checks and premium cloud enhancements.

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✨ Key Features

• Grammar, spelling, and punctuation correction with automatic language detection (core functionality for error-free writing in 30+ languages)
• Style improvements detecting repetitive phrases, word choice issues, and overused terms (enhances readability and professionalism)
• AI-powered paraphrasing to rephrase text for formality, fluency, simplicity, or conciseness (Premium feature)
• Picky Mode for advanced punctuation, style, and typography suggestions (Premium)
• Writing statistics to track errors, suggestions applied, and productivity (monitors improvement)
• Optional: Ongoing community-driven rule updates and experimental neural network enhancements

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🛠 Tech Stack

• Core Engine: Java (91%), Apache Maven for builds
• Server: Standalone HTTP API server (JAR deployment), Docker support
• Clients: Browser extensions (JavaScript for Chrome, Firefox, Edge, etc.), Desktop apps (Windows/macOS integrations), Office add-ins (Google Docs, Microsoft Word, LibreOffice)
• Other: Python, Shell scripts for utilities; self-hosted or cloud-hosted via languagetool.org

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👥 Who Is This For?

This project is useful for:

• Writers who want to refine emails, blogs, tweets, and documents instantly
• Students looking for academic style checks in theses, essays, and papers (with student discounts)
• Teams and businesses seeking consistent multilingual proofreading across tools like Office and browsers

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📸 Screenshots / Demo

• Live demo: https://languagetool.org/
• GitHub: https://github.com/languagetool-org/languagetool

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🔥 Project Status

• 🟢 Actively building

Last updated: 2026-03-24

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❓ FAQ

Is this project free?

Freemium (Explain briefly.) Free version offers basic spelling, grammar, and style checks; Premium ($12/month or discounts for students/nonprofits) unlocks all errors, Picky Mode, unlimited paraphrasing, and priority support.

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Is the source code available?

Yes — link to repository https://github.com/languagetool-org/languagetool (LGPL 2.1+, 14k stars, actively maintained)

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Can I contribute?

Yes — submit issues, PRs for new rules or fixes on GitHub. See https://dev.languagetool.org/development-overview for guidelines. Join the forum at https://forum.languagetool.org for discussion.

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📬 Contact & Links

• Website: https://languagetool.org
• GitHub: https://github.com/languagetool-org/languagetool
• Twitter/X: https://x.com/languagetool
• Email: Via forum or support@languagetool.org (inferred from services)

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