Open Source Grammarly AlternativesGrammar Checkers & AI Writing Tools like Grammarly

The best open source alternative to Grammarly is LanguageTool. It's not free, so if you're looking for a free alternative, you could try Harper or Onit AI. If that doesn't suit you, our users have ranked more than 100 alternatives to Grammarly and many of them is open source so hopefully you can find a suitable replacement. Other interesting open source alternatives to Grammarly are Grammalecte, Vale, Eloquent Proofreading Assistant and Typopo.

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Most Grammarly alternatives are Grammar Checkers, but you can also narrow the list to AI Writing Tools or Text to Speech Services. Other popular filters are Open Source, Windows, iPhone, Linux and Free. You can also filter for EU-based alternatives if you prefer software from the European Union.
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Alternatives
Grammarly alternatives page was last updated

Alternatives list

  1. LanguageTool icon

    LanguageTool

     192 likes

    Proofreading software compatible with LibreOffice, Word, Firefox, and Chrome. Supports 20+ languages, offering two tiers: free and premium, with features like customizable checks, Microsoft add-on, and error detection in gender, ISBN, and IBAN. Offers open-source web and desktop versions.

    134 LanguageTool alternatives

    Cost / License

    Application type

    Since

    • Since 2009

    Platforms

    • Mac
    • Windows
    • Linux
    • Online
    • iPhone
    • iPad
    • Microsoft Edge
    • ONLYOFFICE
    • Google Chrome
    • Microsoft Outlook
    • Safari
    • Visual Studio Code
    • Microsoft Word
    • Eclipse
    • TinyMCE
    • Google Docs
    • Thunderbird
    • Vim
    • Cloudron
    • Sublime Text
    • GNU Emacs
    • Opera
    • Gmail
    • LibreOffice
    • Apache OpenOffice
    • Mozilla Firefox
    • LibreOffice - Writer
    • US flagUnited States
    LanguageTool screenshot 1
    Good alternative?
     
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    11
  2. Harper icon

    Harper

     20 likes

    Harper is an English grammar checker designed to be just right. I created it after years of dealing with the shortcomings of the competition.

    79 Harper alternatives

    Cost / License

    Application type

    Since

    • Since 2025

    Platforms

    • Self-Hosted
    • WebAssembly
    • Visual Studio Code
    • Mac
    • Linux
    • Windows
    • Homebrew
    • Neovim
    • US flagUnited States
    Harper screenshot 1
    Good alternative?
     
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    1
  4. Onit AI icon

    Onit AI

     10 likes

    Onit AI Copilot offers a comprehensive desktop AI chat assistant with local processing and multi-provider support. It prioritizes customization, extensibility, and user privacy by operating entirely on-device without needing an internet connection, ensuring data security.

    64 Onit AI alternatives

    Cost / License

    • Free
    • Open Source

    Since

    • Since 2025

    Platforms

    • Mac
    • US flagUnited States
    Onit AI screenshot 1
    Good alternative?
     
  5. Grammalecte icon

    Grammalecte

     35 likes

    Grammalecte is a French grammar checker.

    Cost / License

    • Free
    • Open Source

    Application type

    Since

    • Since 2016

    Platforms

    • Mac
    • Windows
    • Linux
    • Chrome OS
    • Google Chrome
    • Python
    • Thunderbird
    • Vim
    • Sublime Text
    • GNU Emacs
    • Pluma
    • LibreOffice
    • Mozilla Firefox
    • LibreOffice - Writer
    • ONLYOFFICE
    • FR flagFrance
    • European Union flagEU
    Grammalecte screenshot 1
    Good alternative?
     
  6. Vale icon

    Vale

     2 likes

    Vale is an open-source, command-line tool that brings your editorial style guide to life.

    39 Vale alternatives

    Cost / License

    • Free
    • Open Source (MIT)

    Since

    • Since 2017

    Platforms

    • Windows
    • Mac
    • Linux
    • US flagUnited States
    Vale screenshot 1
    Good alternative?
     
  8. Eloquent Proofreading Assistant icon

    Eloquent Proofreading Assistant

     4 likes

    Eloquent is a proofreading software for English, Spanish, French, German, Portuguese, Polish, Dutch, and more than 20 other languages. It finds many errors that a simple spell checker cannot detect.

    70 Eloquent Proofreading Assistant alternatives

    Cost / License

    Application type

    Since

    • Since 2025

    Platforms

    • Linux
    • Flathub
    • Flatpak
    • US flagUnited States
    Eloquent Proofreading Assistant screenshot 1
    Good alternative?
     
  9. Typopo icon

    Typopo

     2 likes

    Typopo fixes microtypography errors that often require attentive eye and knowledge of local typography rules. It works for English, German, Slovak, Czech and Rusyn texts.

    Cost / License

    • Free
    • Open Source (MIT)

    Since

    • Since 2020

    Platforms

    • Online
    • Software as a Service (SaaS)
    Typopo–online app
    Good alternative?
     
  10. AssisT icon

    AssisT

     1 like

    AssisT is a free, open-source Chrome extension that adds text-to-speech with word-by-word highlighting, speech-to-text, AI writing assistance, and 35+ accessibility features to Canvas LMS, Moodle, Google Classroom, and any website.

    Cost / License

    • Free
    • Open Source

    Application type

    Since

    • Since 2026

    Platforms

    • Google Chrome
    • IE flagIreland
    • European Union flagEU
    Dyslexia Mode
    Good alternative?
     
  11. Editsaurus icon

    Editsaurus

     15 likes

    Highlights potential pitfalls in your writing to encourage good habits.

    Cost / License

    • Free
    • Open Source (MIT)

    Application type

    Since

    • Since 2016

    Alerts

    • Discontinued

    Platforms

    • Online
    • Self-Hosted
    • US flagUnited States
    Editsaurus screenshot 1
    Good alternative?
     
  12. P

    proselint

     2 likes

    Writing is notoriously hard, even for the best writers, and it's not for lack of good advice — a tremendous amount of knowledge about the craft is strewn across usage guides, dictionaries, technical manuals, essays, pamphlets, websites, and the hearts and minds of great...

    Cost / License

    Since

    • Since 2019

    Platforms

    • Linux
    • Python
    Good alternative?
     
  13. RewritePal icon

    RewritePal

     6 likes

    RewritePal is a free, AI-powered tool designed to make your writing clear, compelling, and tailored to any audience. Whether you're a student, professional, or content creator, RewritePal helps you transform paragraphs into polished, reader-friendly text in seconds.

    Cost / License

    • Free
    • Open Source (MIT)

    Application type

    Since

    • Since 2025

    Platforms

    • Online
    RewritePal screenshot 1
    Good alternative?
     
  14. Grammark icon

    Grammark

     2 likes

    Grammark helps improve writing style & grammar and teaches students to self-edit. Basically, it finds things that grammarians consider bad, highlights them, and suggests improvements.

    Cost / License

    Application type

    Since

    • Since 2018

    Platforms

    • Online
    • Self-Hosted
    Good alternative?
     
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    2
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