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Preview of Private Grammar Checker - Harper

Private Grammar Checker - Harper by Elijah Potter

A private grammar checker for 21st Century English

4.8 (17 reviews)4.8 (17 reviews)
645 Users645 Users
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Harper - Grammar Checking that Respects Your Privacy

Harper helps your writing shine everywhere you write.Harper was written from the ground-up to be fast, so it can get out of your way.
About this extension
Harper is a fast, privacy-first grammar and spelling checker that works entirely offline. No cloud. No tracking. No ads. Just clean, real-time feedback as you write.

Harper is designed for performance and precision. It checks your grammar and spelling across websites, documents, and comment fields — without sending a single keystroke to the internet.

Who it's for:
• Writers who want accurate grammar help without giving up privacy
• Developers writing technical docs, READMEs, or blog posts
• Markdown lovers, privacy advocates, and minimalists
• Anyone tired of bloated grammar checkers and upsells

Key features:
• ✅ Grammar and spelling suggestions in real time
• 🔒 100% offline – your text never leaves your machine
• 🌎 Supports American 🇺🇸, British 🇬🇧, Canadian 🇨🇦, and Australian 🇦🇺 English
• 💻 Great for Markdown, documentation, and code comments
• 🚫 No popups, ads, or feature nags
• 🛠️ Open source – inspect and contribute on GitHub
• ⚡ Built in Rust for speed and memory efficiency

Unlike tools that harvest your data, Harper runs entirely in your browser — fast, secure, and unobtrusive. You write. Harper keeps it clean.
Rated 4.8 by 17 reviewers
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Permissions and dataLearn more

Required permissions:

  • Access browser tabs
  • Access your data for all web sites
More information
Add-on Links
  • Homepage
  • Support site
Version
0.56.0
Size
5.64 MB
Last updated
7 days ago (6 Aug 2025)
Related Categories
  • Language Support
  • Social & Communication
Licence
Apache Licence 2.0
Version History
  • See all versions
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Release notes for 0.56.0
View main release notes here: https://github.com/Automattic/harper/releases/tag/v0.56.0
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