head to head · open source
slate vs Harper
slate has 31,747 GitHub stars, 3,306 forks, 653 open issues and last shipped 6 days ago. Harper has 17,365 stars, 794 forks, 896 open issues and last shipped yesterday. slate leads on adoption by 83% (31,747 vs 17,365 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 5%. 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 | ★ 17K |
| License | MIT | Apache-2.0 |
| Written in | TypeScript | Rust |
| Last push | 2026-10-28 | 2026-11-02 |
| Forks | ⑂ 3.3K | ⑂ 794 |
| 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
A completely customizable framework for building rich text editors. Why? · Principles · Demo · Examples · Documentation · Contributing! Slate lets you build rich, intuitive editors like those in Medium, Dropbox Paper or Google Docs—which are becoming table stakes for applications on the web—without your codebase getting mired in complexity. It can do this because all of its logic is implemented with a series of plugins, so you aren't ever constrained by what is or isn't in "core". You can think of it like a pluggable implementation of contenteditable built on top of React. It was inspired by libraries like…
read the full slate overview →
About Harper
Harper 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…
read the full Harper overview →
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Frequently asked questions
Is slate or Harper more popular?
slate has 31,747 GitHub stars and Harper has 17,365. 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 (31,747 stars) or its MIT licence terms. Choose Harper if its feature set, stack or Apache-2.0 licence fits better. Both are self-hostable.