Automattic/harper
★ 16,756 stars
Covered in week 2026-W27 · the 2026-06 report
Offline, privacy-first grammar checker. Fast, open-source, Rust-powered
What harper is
Harper is an English grammar checker designed to be just right. I created it after years of dealing with the shortcomings of the competition.
From the repository README · read it on GitHub →
Transcript
Grammarly Premium drains $30 monthly. Harper spots every writing mistake on your computer privately. You scan emails and fix documents without them ever leaving your device. Errors vanish in milliseconds right where you type—browsers, apps, everywhere. Install on your laptop, desktop, and phones. Your paragraphs stay yours alone—no cloud processing, no data mining. You polish reports, posts, and messages without surveillance. Over 10,900 developers trust this free alternative. Would you swap paid subscriptions for this local guardian?