GrammarCheck.ai vs Harper

GrammarCheck.ai checks grammar, spelling, and punctuation, highlighting mistakes and suggesting replacements; a one-click “Fix All Errors” action is also listed. It supports English variants for the US, UK, Australia, and Canada, as well as Spanish, German, French, Portuguese, Italian, and Dutch. Other listed tools include punctuation checking, paraphrasing, plagiarism checking, AI detection, AI humanizing, and summarizing. The service is available on web, iOS, Android, and Linux, with browser extension, desktop app, and mobile app options. Its free plan allows up to 650 words per submission, while Lite allows 2,000 and Pro 6,000. The plans list $4 a month for Lite and $7 a month for Pro; the pricing note separately says paid plans start at $2.50/mo (annual). The service does not offer a free trial, though tools can be used for free. Guest users can make three submissions per minute. The site identifies students, book authors, bloggers, and non-native English speakers as potential users.

Harper is a free, open-source grammar checker that flags capitalization, spelling, awkward phrasing, and grammar errors. The maker says checks run locally, with no cloud round-trips, telemetry, or LLM in the loop, and that suggestions appear in under 10 ms. Harper is available through browser and editor extensions, a language server, a JavaScript library, a Rust crate, and native apps. Listed integrations include Chrome, Brave, Edge, Firefox, VS Code, Cursor, Obsidian, WordPress, Neovim, Zed, Helix, Emacs, and Sublime Text. Its language support covers English and British, American, Canadian, Australian, and Indian English dialects. Harper Desktop lets users toggle rules, add dictionary entries, select a dialect, and turn checking on or off per app. The desktop app is labeled beta for macOS 14 or later, and the Windows desktop app is also described as a beta; its binary was not signed at the time of the listed post. Harper is free, with no account or credit card required.