The company behind WordPress built a Grammarly alternative that never sends your text anywhere
Three open-source writing checkers, all of which shipped code within a day of this article. One of them is maintained by Automattic — and it works with no connection at all.
TL;DR — the short version
Three open-source alternatives, all alive. LanguageTool, Harper and Vale each received new code within twenty-four hours of this page being written.
Harper is maintained by Automattic — the company behind WordPress — and its own description reads “offline, privacy-first grammar checker”. Nothing you type leaves your computer.
They are not interchangeable. LanguageTool replaces Grammarly. Harper replaces the part of Grammarly you may not want in the cloud. Vale does something Grammarly does not do at all.
A cloud grammar checker works the only way a cloud grammar checker can: the sentence you are writing is sent to a server, analysed there, and suggestions come back. That is the architecture, not an accusation. It is also why the same tool is banned outright in some legal and medical workplaces.
If that trade-off suits you, Grammarly is a polished product and there is no reason to leave it. If it does not — or if you simply would rather not pay a monthly fee to check your spelling — there are three credible open-source answers. We checked all three the morning this was published.
LanguageTool — the direct replacement
LanguageTool is the closest thing to a drop-in swap. Browser extension, desktop apps, plugins for the usual editors, and support for dozens of languages rather than English alone — which matters if you write in more than one.
It runs as a hosted service with a free tier, and, because it is open source under LGPL-2.1, you can also run the whole checker on your own server. Companies with a policy against sending text outside the building take that second route.
14,781 stars, last commit the day this was written. It is one of the oldest projects in this category and one of the most consistently maintained.
Harper — the offline one, and the surprise
Harper is the reason this article exists. It is maintained by Automattic, the company behind WordPress, and its repository describes it in six words: offline, privacy-first grammar checker.
Written in Rust, it is fast enough to check as you type without a round trip to anywhere. There is no account, no upload, and no network call — the analysis happens in the editor. For a contract, a medical note or an internal HR email, that is not a detail.
14,282 stars, last commit the day before this was written. Started in October 2023, it has accumulated roughly thirteen stars a day, every day, since — steady rather than explosive, which in this field usually means the people building it intend to keep going.
The oddity worth noting: it is backed by one of the largest companies on the open web, and outside developer circles almost nobody has heard of it.
Vale — not a Grammarly replacement at all
Vale belongs on this list for a different reason. It does not tell you that a sentence is wrong; it tells you that a sentence breaks your rules. You write the style guide — banned words, preferred spellings, tone, heading conventions — and Vale enforces it across every document, in a text editor or automatically before publication.
That is a job Grammarly does not do. If you are one writer, you probably do not need it. If you are a team of eight trying to sound like one company, it is the only tool here that solves your actual problem.
5,758 stars, last commit the day before this was written. MIT licensed.
Which one, in one line each
- You want to stop paying and keep the same habits — LanguageTool. Install the browser extension and carry on.
- Your writing must not leave your machine — Harper. No account, no upload, no network call.
- Your team needs to sound like one voice — Vale, alongside one of the other two.
Nothing stops you running two. Harper and Vale answer different questions and do not compete for the same slot.
What we did not check
We measured what is measurable: licences, star counts and the date of the last commit, taken from the public repositories on 9 August 2026. We did not benchmark suggestion quality, and we did not compare prices — Grammarly’s plans change and we have not verified their current grid.
One caveat on stars: they only ever accumulate. A project that stopped two years ago keeps every star it earned, which is why the most-starred tool in a category is so often the abandoned one. That is the whole reason we publish the commit date next to it.
Method
Three repositories, queried through the GitHub API on 9 August 2026: languagetool-org/languagetool, Automattic/harper and errata-ai/vale. Stars and last push are read directly from each repository; licences are the SPDX identifiers GitHub reports.
The shortlist itself comes from our Grammarly alternatives page, which is rebuilt from the catalogue rather than written by hand — and which now lists all three.