AuthorWritten in Rust, everything is processed in an instant and I find it neat to see the browser extension highlight words as I type, effectively checking per letter. And no account is required, allowing me to get up and running in no time.
Hi. I'm Harper.
The Free Grammar Checker That Respects Your Privacy
What is it?
Harper is a free English grammar checker designed to be just right. You can think of it as an open-source alternative to Grammarly. I created it after years of dealing with the shortcomings of the competition.
Private
Harper is completely private, in every sense of the word.
Since Harper runs on-device, your data doesn't go anywhere you don't want it to.
That means you have 100% certainty we don't violate your copyright by training large language models.
Native Everywhere
Harper is available as a language server, JavaScript library through WebAssembly, and Rust crate, so you can get fantastic grammar checking anywhere you work.
That said, we take extra care to make sure the Visual Studio Code, Neovim, Obsidian, and Chrome extensions are amazing.
Wicked Fast
Since Harper runs on your devices, it's able to serve up suggestions in under 10 milliseconds.
No network request, no massive language models, no fuss.
Loved by Thousands
Obsidian is my favorite productivity app, and Harper is a grammar checking tool that works well with it.
Awesome extension! It's privacy focused, that means that every check it done locally on your computer, there is no server where your data goes! And because of that it's blazingly fast compared to Grammarly.
Harper is great: it is discreet, fast, powerful, and private.
What I loved about this tool is that it's private, and open source and really fast.
I've been using Harper in Neovim for a long time and am glad to see it as an extension!
What a delightful way to check for flagrant spelling errors in markdown files. Thanks Harper authors!
Harper excels at catching the kinds of mistakes that matter in technical writing – improper capitalization, misspelled words, and awkward phrasing that can make documentation unclear.
I've been using Harper instead of Grammarly for a few months already, and I can't be happier! I can't wait to see the great improvement when this tool reaches version 1.0.0! Great job! I hope that, eventually, it will also support languages other than English.
FAQs
Is Harper Free?
Yes. Harper is free in every sense of the word. You don't need a credit card to start using Harper, and the source code is freely available under the Apache-2.0 license.
How Does Harper Work?
Harper watches your writing and provides instant suggestions when it notices a grammatical error. When you see an underline, it's probably because Harper has something to say.
Does Harper Change The Meaning of My Words?
No. Harper will never intentionally suggest an edit that might change your meaning. Harper strives to never make it harder to express your creativity.
Is Harper Really Private?
Harper is the only widespread and comprehensive grammar checker that is truly private. Your data never leaves your device. Your writing should remain just that: yours.
How Do I Use or Integrate Harper?
That depends on your use case. Do you want to use it within Obsidian? We have an Obsidian plugin. Do you want to use it within WordPress? We have a WordPress plugin. Do you want to use it within your Browser? We have a Chrome extension and a Firefox plugin. Do you want to use it within your code editor? We have documentation on how you can integrate with Visual Studio Code and its forks, Neovim, Helix, Emacs, Zed and Sublime Text. If you're using a different code editor, then you can integrate directly with our language server, harper-ls. Do you want to integrate it in your web app or your JavaScript/TypeScript codebase? You can use harper.js. Do you want to integrate it in your Rust program or codebase? You can use harper-core.
What Human Languages Do You Support?
We currently only support English and its dialects British, American, Canadian, and Australian. Other languages are on the horizon, but we want our English support to be truly amazing before we diversify.
What Programming Languages Do You Support?
For harper-ls and our code editor integrations, we support a wide variety of
programming languages. You can view all of them over at the harper-ls documentation.
We are entirely open to PRs that add support. If you just want to be able to run grammar checking
on your code's comments, you can use this PR as a model for what to do.
For harper.js and those that use it under the hood like our Obsidian plugin, we
support plaintext and/or Markdown.
Where Did the Name Harper Come From?
See this blog post.
Do I Need a GPU?
No. Harper runs on-device, no matter what. There are no special hardware requirements. No GPU, no additional memory, no fuss.
Open Source
Harper is completely open source under the Apache-2.0 license.
Come pay us a visit on GitHub.