Offline, privacy-first grammar checker. Fast, open-source, Rust-powered
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Elijah Potter b642c99212
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hotfix(core): properly format example
2025-12-09 11:40:02 -07:00
.github fix(ci): cache intermediate layers 2025-11-18 13:23:01 -07:00
.vscode chore: mostly annotating verbs and nouns (#1874) 2025-09-08 12:20:49 +00:00
fuzz fuzz: add example fuzzing targets (#1949) 2025-11-19 20:00:40 +00:00
harper-brill Release 1.1.0 2025-12-03 12:31:42 -07:00
harper-cli Release 1.0.0 2025-11-28 12:52:07 -07:00
harper-comments build(deps): bump tree-sitter-bash from 0.25.0 to 0.25.1 (#2304) 2025-12-08 15:26:18 +00:00
harper-core hotfix(core): properly format example 2025-12-09 11:40:02 -07:00
harper-html Release 1.1.0 2025-12-03 12:31:42 -07:00
harper-ink Release 1.1.0 2025-12-03 12:31:42 -07:00
harper-jjdescription Release 1.1.0 2025-12-03 12:31:42 -07:00
harper-literate-haskell Release 1.1.0 2025-12-03 12:31:42 -07:00
harper-ls fix(ls): prevent panic when workspace/configuration is unsupported (#2309) 2025-12-08 16:08:16 +00:00
harper-pos-utils Release 1.1.0 2025-12-03 12:31:42 -07:00
harper-python Release 1.1.0 2025-12-03 12:31:42 -07:00
harper-stats Release 1.1.0 2025-12-03 12:31:42 -07:00
harper-tree-sitter Release 1.1.0 2025-12-03 12:31:42 -07:00
harper-typst Release 1.1.0 2025-12-03 12:31:42 -07:00
harper-wasm feat(core): create rule to title-case headings (#2297) 2025-12-05 20:35:00 +00:00
packages feat(core): create rule to title-case headings (#2297) 2025-12-05 20:35:00 +00:00
.dockerignore fix: dockerfile issues 2025-03-19 11:51:08 +08:00
.editorconfig feat: enforce LF line endings everywhere 2025-03-10 10:51:39 -06:00
.envrc feat(devshell): init devshell 2025-04-04 16:06:31 -04:00
.gitattributes fix: ignore test dataset files from source code line count 2025-11-28 13:25:20 -07:00
.gitignore refactor(web): build out feedback mechanisms (#2069) 2025-10-22 11:37:49 -06:00
.node-version chore(node): use lts/* instead of lts/iron 2025-02-03 16:54:14 +08:00
.npmrc fix: dockerfile issues 2025-03-19 11:51:08 +08:00
ARCHITECTURE.md docs: moved architecture document to the web 2024-12-27 12:03:11 -07:00
biome.json chore: reduce dependency load for new contributors (#2131) 2025-11-04 13:53:01 -07:00
Cargo.lock build(deps): bump tree-sitter-bash from 0.25.0 to 0.25.1 (#2304) 2025-12-08 15:26:18 +00:00
Cargo.toml fuzz: add example fuzzing targets (#1949) 2025-11-19 20:00:40 +00:00
COMPARISON.md fix: changed links from elijah-potter/harper to automattic/harper 2024-12-18 08:05:16 -07:00
CONTRIBUTING.md docs: moved contributor documentation to the web 2024-12-27 11:49:08 -07:00
demo.md feat(web): make demo more enticing 2025-09-24 08:09:14 -06:00
docker-compose.dev.yml refactor(web): build out feedback mechanisms (#2069) 2025-10-22 11:37:49 -06:00
docker-compose.yml refactor(web): build out feedback mechanisms (#2069) 2025-10-22 11:37:49 -06:00
Dockerfile feat: create component library + use in relevant places (#2229) 2025-11-24 09:45:05 -07:00
flake.lock Add wasm-bindgen-cli to nix flake (#2108) 2025-10-27 15:49:28 +00:00
flake.nix chore: reduce dependency load for new contributors (#2131) 2025-11-04 13:53:01 -07:00
justfile feat: create component library + use in relevant places (#2229) 2025-11-24 09:45:05 -07:00
LICENSE fix: filled in LICENSE 2024-03-25 14:58:52 -06:00
logo.svg feat: added logo to README.md and web client 2024-02-15 20:56:27 -07:00
package.json chore: reduce dependency load for new contributors (#2131) 2025-11-04 13:53:01 -07:00
pnpm-lock.yaml refactor(core): remove implementation details from public API (#2256) 2025-11-28 12:36:04 -07:00
pnpm-workspace.yaml refactor(core): remove implementation details from public API (#2256) 2025-11-28 12:36:04 -07:00
README.md feat: add download badges 2025-10-07 11:23:26 -06:00
rust-toolchain.toml feat: enforce stable rust with a rust-toolchain.toml 2024-09-27 08:28:57 +02:00
rustfmt.toml feat(core): added Whereas rule 2025-02-06 08:57:02 -07:00
test.md feat(core): create rule to detect incorrect verbs in nominal phrase (#2176) 2025-11-13 15:32:54 -07:00

Harper

Harper Binaries Website Checks Crates.io NPM Version Downloads Obsidian Plugin Downloads

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 created Harper: it is the grammar checker that fits my needs. Not only does it take milliseconds to lint a document, take less than 1/50th of LanguageTool's memory footprint, but it is also completely private.

Harper is even small enough to load via WebAssembly.

Language Support

Harper currently only supports English, but the core is extensible to support other languages, so we welcome contributions that allow for other language support.

Performance Issues

We consider long lint times bugs. If you encounter any significant performance issues, please create an issue on the topic.

If you find a fix to any performance issue, we would appreciate the contribution. Just please make sure to read our contribution guidelines first.

Huge Thanks

This project would not be possible without the hard work from those who contribute.

Harper's logo was designed by Lukas Werner.