About
A Rust-based, offline, privacy-first English grammar and spell checker (rule-based; under 10 ms suggestions, about 1/50th of LanguageTool's memory). Ships as a language server (harper-ls), VS Code/Neovim/Helix/Emacs/Zed extensions, browser extensions, Obsidian plugin, macOS desktop app, and WASM (harper.js). English only, and rule-based coverage is narrower than Grammarly. Completely free, no account, no telemetry, no cloud — all checking happens on-device.
Install the editor extension (VS Code/Neovim marketplace) or browser extension; or build from source:
cargo build --releaseMore in CLI Tools
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