LanguageTool
A grammar, spelling and style checker for more than 30 languages, with a free plan.
Browser ExtensionFree planChrome, Firefox
4.6Visit
Browser Extension
Harper
A free, open-source grammar checker that runs entirely on your device.
Built with love by Shushant Lakhyani. Building bestproductivityresources.com
What is Harper?
Harper is a private grammar checker for English that runs on your own machine, with no cloud round-trips, telemetry or large language model, so your writing never leaves your device. It is free and open source under the Apache 2.0 licence. Harper was created by Elijah Potter, who now builds it at Automattic. It is available as a desktop app for macOS, browser extensions for Chrome, Edge and Firefox, and plugins for VS Code, Neovim, Zed, Obsidian and WordPress. It currently supports English only, including British, American, Canadian, Australian and Indian English.
Pros
- Completely free and open source (Apache 2.0)
- Private: checks run on your device, nothing is sent anywhere
- Works in browsers, code editors, Obsidian and WordPress
Cons
- English only for now
- No AI rewriting or tone suggestions
Who should use Harper
Privacy-minded writers and developers who want fast, local grammar checks.
Who may not need it
People who write in languages other than English.
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