head to head · open source
slate vs Harper
slate has 31,748 GitHub stars, 3,302 forks, 653 open issues and last shipped 5 days ago. Harper has 15,469 stars, 632 forks, 896 open issues and last shipped yesterday. slate leads on adoption by 105% (31,748 vs 15,469 stars). slate is written in TypeScript under MIT; Harper is written in Rust under Apache-2.0. slate has attracted 10% as many forks as stars, Harper 4%. Harper was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 1 topic tag (react), so they are genuine substitutes rather than adjacent tools.
Two open source projects, one decision. Both are free and self-hostable — the differences are community size, license terms, language stack and release pace.
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Side by side
| slate | Harper | |
|---|---|---|
| GitHub stars | ★ 32K | ★ 15K |
| License | MIT | Apache-2.0 |
| Written in | TypeScript | Rust |
| Last push | 2026-09-13 | 2026-09-17 |
| Forks | ⑂ 3.3K | ⑂ 632 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick slate if
- You weight community size — 32K stars and counting
- You want the MIT license terms
- Your stack matches TypeScript
- You value the larger contributor base for long-term maintenance
pick Harper if
- You want the Harper feature set and don't need the biggest community
- You prefer the Apache-2.0 license terms
- Your stack matches Rust
- You evaluated both and Harper fits your workflow better
About slate
Slate is a completely customizable framework for building rich text editors, written in TypeScript and released under the MIT licence, for JavaScript and React developers who need an editor that goes well past what a fixed schema can offer.
read the full slate overview →
About Harper
Harper is offline, privacy first grammar checker for English. It lives in productivity, browser extension, developer tools, and text editing ecosystem. Project is open source under Apache 2.0. GitHub metadata shows 15373 stars, 627 forks, and 896 open issues. Last push is 2026 09 14. Category is Productivity & Utilities / Browsers & Extensions. It uses Rust for core, WebAssembly for browser loading, language server for editors, JavaScript package for web and Node.js apps. It solves slow, costly, network dependent grammar checking. It replaces Grammarly and LanguageTool as named in README. Grammarly sends writing …
read the full Harper overview →
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Frequently asked questions
Is slate or Harper more popular?
slate has 31,748 GitHub stars and Harper has 15,469. slate has the larger community by that measure.
Are slate and Harper free?
Both are open source. slate is licensed under MIT and Harper under Apache-2.0. Neither carries a licence fee.
What is the difference between slate and Harper?
slate is written in TypeScript and Harper in Rust. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, slate or Harper?
Choose slate if you want the larger community (31,748 stars) or its MIT licence terms. Choose Harper if its feature set, stack or Apache-2.0 licence fits better. Both are self-hostable.