Alternatives to Harper
An open-source grammar and spell checker that runs entirely on your own device. The listings below can replace it for an important use case. Each note says what changes if you switch.
The original
Harper
An open-source grammar and spell checker that runs entirely on your own device.
Replacements
Listings that take over the same core job as Harper.
Grammarly
An AI writing assistant that checks grammar and spelling and suggests rewrites and tone changes.
Grammarly adds AI rewrites, tone suggestions and an AI detector, but it requires an account, processes text on its servers and is proprietary.
Writing Tools
A system-wide desktop app that proofreads, rewrites and summarizes selected text with cloud or local LLMs.
Writing Tools is also open source and can use local LLMs to proofread and rewrite selected text on Windows, macOS and Linux, though output depends on the model.
Linguix
A grammar checker and AI rewriting assistant that works on websites through a browser extension and web editor.
Linguix checks grammar in seven languages and adds a sentence rewriter and team style guides, but it needs an account and processes text online.
Ginger
An AI writing assistant that corrects grammar, rephrases sentences and suggests synonyms in browsers and apps.
Ginger adds rephrasing, synonyms and Microsoft Office support on Windows with Android and desktop apps, but it is not open source and checks text online.
Outwrite
A grammar, style and paraphrasing assistant that works in the browser and common writing apps.
Outwrite adds paraphrasing and readability statistics in Docs, Gmail, Word and Outlook and supports French and Spanish, but it processes text in the cloud and is proprietary.
ProWritingAid
A grammar checker and style editor with planning and critique tools aimed at fiction writers.
ProWritingAid adds style and line-editing feedback with fiction planning tools across Word, a desktop editor and browser, but it is proprietary and the full feature set is paid.
QuillBot
An AI writing tool for paraphrasing, grammar checking, summarizing and generating citations.
QuillBot adds paraphrasing, summarizing and citation tools with Windows and mobile apps, but it processes text on QuillBot's servers and advanced modes need Premium.
Also worth comparing
These listings name Harper as their own alternative, so the relationship runs both ways.
Trinka
An AI grammar checker and writing assistant aimed at academic and technical writing.
Harper is a free, open-source checker that runs entirely on your device with no telemetry, but it is rule-based, English only and lacks academic tuning.
Writefull
AI language feedback, paraphrasing and copyediting tuned for academic writing, with Word and Overleaf plugins.
Harper is free and open source, runs locally with no telemetry and works as a language server for editors, but is rule-based and not academic-focused.
Similar software
Related functionality, not a direct replacement.
Hemingway Editor
Writing editor that highlights complex sentences and other issues to make text clearer and bolder.
Readable
An online readability checker that scores text with many readability formulas and highlights passages to fix.
Wordtune
An AI writing assistant that suggests rewrites, adjusts tone and proofreads English text.
