Automattic/harper
Offline, privacy-first grammar checker. Fast, open-source, Rust-powered
From the publisher
README & documentation
Source previewRead the project’s overview, installation instructions and usage examples. The original README is the source of truth.
[](https://github.com/automattic/harper/actions/workflows/binaries.yml) [](https://github.com/automattic/harper/actions/workflows/buildweb.yml) [](https://github.com/automattic/harper/actions/workflows/justchecks.yml) [](https://crates.io/crates/harper-ls) Harper is an English grammar checker designed to be just right. I created it after years of dealing with the shortcomings of the competition. Grammarly was too expensive and too overbearing. Its suggestions lacked context, and were often just plain wrong. Not to mention: it's a privacy nightmare. Everything you write with Grammarly is sent to their servers. Their privacy policy claims they don't sell the data, but that doesn't mean they don't use it to train large language models and god knows what else. Not only that, but the round-trip-time of the network request makes revising your work all the more tedious. 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. That's why I…
Read the full README ↗ · Preview checked 2026-10-27T03:29:20.357Z
Inside the original README — Document outline
Headings are captured from the source. Links open the publisher’s document, not a locally hosted copy.
Links from the README
References supplied by the publisher, not independently verified endorsements. Check the destination before downloading files or entering credentials.
Documentation belongs to its respective authors. Reported project/model license: Apache-2.0. A listing is not a grant of reuse or training rights. Confirm the document’s own terms at the source.
What this repository does
Offline, privacy-first grammar checker. Fast, open-source, Rust-powered
Repository facts
- Owner
- Automattic
- Primary language
- Rust
- Stars
- 17,331
- Forks
- 788
- Open issues + pull requests
- 1,010
- License
- Apache-2.0
- Archived
- No
- Default branch
- master
- Created
- 2023-10-22T02:58:35.000Z
- Last push
- 2026-10-31T11:08:34.000Z
Topics and intended use
Owner-supplied topics: chrome-extension, developer-tools, english-language, grammar-checker, nodejs, react, rust, svelte, webassembly
Review the README for scope, installation, examples and limitations. We do not run repository code or certify it.
Evaluate before installing
Review licensing and dependencies, inspect recent commits and unresolved issues, and test in an isolated environment before production use. Stars and forks alone cannot answer these questions.
Source and freshness
Source: GitHub. Metadata observed 2026-11-01T12:19:46.836Z. Daily imports are snapshots, not real-time monitoring.
Popularity and source listings do not establish security, suitability, licensing rights or benchmark performance.