116 releases (14 stable)

Uses new Rust 2024

2.0.0 Apr 9, 2026
1.12.0 Mar 19, 2026
1.9.0 Feb 27, 2026
1.3.0 Dec 22, 2025
0.8.3 Mar 25, 2024

#570 in Text processing

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1,131 downloads per month
Used in 13 crates

Apache-2.0

6.5MB
75K SLoC

harper-core

harper-core is the fundamental engine behind Harper, the private grammar checker.

harper-core is available on crates.io to enable Rust engineers to integrate high-quality grammar checking directly into their apps and workflows. Feel free to use harper-core in your projects. If you run into problems with the code, open an issue or, even better, create a pull request. We are also happy to chat with you on Discord.

The documentation for harper-core is available online.

If you would prefer to run Harper from inside a JavaScript runtime, we have a package for that as well.

Example

Here's what a full end-to-end linting pipeline could look like using harper-core.

use harper_core::linting::{LintGroup, Linter};
use harper_core::parsers::PlainEnglish;
use harper_core::spell::FstDictionary;
use harper_core::{Dialect, Document};

let text = "This is an test.";
let parser = PlainEnglish;

let document = Document::new_curated(text, &parser);

let dict = FstDictionary::curated();
let mut linter = LintGroup::new_curated(dict, Dialect::American);

let lints = linter.lint(&document);

for lint in lints {
    println!("{:?}", lint);
}

Features

concurrent: Whether to use thread-safe primitives (Arc vs Rc). Disabled by default. It is not recommended unless you need thread safety (i.e. you want to use something like tokio).

Other Relevant Packages

Dependencies

~80–120MB
~2M SLoC