Harper

Automattic/harper

Offline, privacy-first grammar checker. Fast, open-source, Rust-powered

Grammar checkPrivacyBrowser extension

Harper website screenshot

From the README

Harper is an English grammar checker designed to be just right. I created it after years of dealing with the shortcomings of the competition.

Stars: ★ 15.8k
Language: Rust
License: Apache-2.0
Last updated: 2026-09-23
Category: Writing & notes
Section: General

Get the add-on Repository