Google’s Grammar checker works completely offline.[1]

[1]https://ai.googleblog.com/2021/10/grammar-correction-as-you-...

(Disclosure: I work at Google)

Thanks for the pointer. This is an impressive job - reducing a grammar correcting model to as much as 20MB. Theoretically this could even be shipped to browsers and if we are able to wrap it in an extension that works everywhere, this could seriously compete with Grammarly.

I could understand why Google wouldn't open-source this tech, but the blog pretty much covers how to build one. I'm surprised there isn't any open source project that took this direction to bring a privacy-focused grammar checker.

Word 97 had grammar checking and wouldn't have used an online service for that.

And it's pretty bad. It works half decently on English, because the English grammar is rather inflexible, but for languages with more variation in word order the Office grammar checkers were laughably bad. They could only spot a few errors, and those were not even relevant to bad writers.

I'm not blaming anyone, the constraints made it nearly impossible, and at the time there wasn't enough properly tagged corpus material to work with, not even for English.

Similarly, macOS has had basic local grammar checking for text fields in native apps and Safari for around a decade now.

https://github.com/languagetool-org/languagetool is pretty good for grammar. It's quite trivial to work with the REST API, try one of the docker images.

In French, Grammalecte [1] is open source, works quite well and works offline.

[1] https://grammalecte.net/

”LanguageTool is an Open Source proofreading software for English, French, German, Polish, Russian, and more than 20 other languages. It finds many errors that a simple spell checker cannot detect.”

https://github.com/languagetool-org/languagetool https://languagetool.org/

After Grammarly stopped the service for users from Russia, I switched to LanguageTool, but found the experience much more lacking. It often suggests weird "fixes", for example replacing "look" with "onion", apparently because that's how "onion" in russian sounds.

Hemingway Editor is one such app that may provide what you seek. [1] It's not Open Source, but it isn't expensive for what it does. It's a fixed price for purchase, not an ongoing subscription.

[1] https://hemingwayapp.com/

>. It's a fixed price for purchase, not an ongoing subscription.

...and that is nowadays what i base my software choices (including mobile/ android) on.

The alternative to basically keyloggers does not necessarily have to be open source or offline. See other comments on Hemingway. Microsoft has also modern grammar checks now built into Word 365 / Outlook 365. They work as good as Grammarly without increasing trust surface. If you already are trusting the documents to Microsoft - might as well allow them to grammar check.

Once, when I saw someone using Grammarly during a screen presentation, I took an instant mental note to self-censor when chatting with that Person in the future, because this person does not care about digital privacy like I do and will broadcast at least parts of our conversations.