4 open-source Writing Assistance & Grammar vendors.

Open-source software for Writing Assistance & Grammar that you can self-host, with auditable source code — regardless of the developer's headquarters.

• CKEditorSelf-hosted / open source

  Rich text editor developed by CKSource (legally headquartered in Warsaw, Poland, ul. Okopowa 58/72), distributed under a dual GPL/commercial licence. Actively sold in 2026 with integrated AI features (AI Chat, AI Review, AI Translate, AI Quick Actions) that keep human review control over AI-generated edits.

  Poland

• LanguageToolEU-hosted, non-EU parent

  German open-source grammar, spelling, and style checker supporting 30+ languages

  Germany · owner in United States

• Notepad++Self-hosted / open source

  Free open-source text and source code editor for Windows with syntax highlighting and plugins.

  France

• Sapling AISelf-hosted / open source

  US open-source language-model toolkit for grammar, autocomplete and AI detection.

  United States