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Harper: Free, Open Source Grammar Checker (writewithharper.com)
submitted 1 month ago by cm0002@suppo.fi to c/opensource@programming.dev
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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.

Harper also intentionally avoids including any kind of generative AI in any part of our processing pipeline.

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[-] BlueKey@fedia.io 6 points 1 month ago

How does it compare to Languagetool (which you can also run locally)?

[-] moonpiedumplings@programming.dev 8 points 1 month ago

Languagetool's browser extension is no longer open source, which has me concerned. You can still point it at a local server, but yeah.

[-] Flagstaff@programming.dev 1 points 1 month ago

Interesting, TIL, thanks. Guess I'll switch...

[-] Successful_Try543@feddit.org 6 points 1 month ago

LT supports also languages other than English, Harper doesn't.

[-] _hovi_@lemmy.world 4 points 1 month ago

From the readme:

LanguageTool is great, if you have gigabytes of RAM to spare and are willing to download the ~16GB n-gram dataset. Besides the memory requirements, I found LanguageTool too slow: it would take several seconds to lint even a moderate-size document.

Seems interesting, even if it's still early in development. I'll certainly be trying out the language server in my neovim setup anyway.

this post was submitted on 25 Nov 2025
91 points (100.0% liked)

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