Harper Grammar Checker

Harper is a privacy-focused, open-source grammar and spell checker designed to run entirely offline on a user's device. Created as a developer-friendly alternative to cloud-based services like Grammarly, Harper was originally developed in Rust to ensure high performance and data sovereignty. It integrates with various environments including VS Code, Neovim, Obsidian, and web browsers like Chrome and Firefox.

In November 2024, the brand was acquired by Automattic, the company behind WordPress.com and Tumblr. This acquisition integrated Harper into Automattic's ecosystem of content creation tools, specifically targeting developers and technical writers who require secure, local-first grammar checking. As a software product, it is distributed globally through digital platforms and developed by a distributed team of contributors led by Automattic.