head to head · open source
readest vs substance
readest has 25,874 GitHub stars, 1,805 forks, 145 open issues and last shipped yesterday. substance has 2,738 stars, 121 forks, 41 open issues and last shipped 7 months ago. readest leads on adoption by 845% (25,874 vs 2,738 stars). readest is written in TypeScript under AGPL-3.0; substance is written in JavaScript under MIT. readest has attracted 7% as many forks as stars, substance 4%. readest was the more recently maintained of the two, and both are self-hostable with no licence fee.
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
| readest | substance | |
|---|---|---|
| GitHub stars | ★ 26K | ★ 2.7K |
| License | AGPL-3.0 | MIT |
| Written in | TypeScript | JavaScript |
| Last push | 2026-11-02 | 2026-04-02 |
| Forks | ⑂ 1.8K | ⑂ 121 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick readest if
- You weight community size — 26K stars and counting
- You want the AGPL-3.0 license terms
- Your stack matches TypeScript
- You value the larger contributor base for long-term maintenance
pick substance if
- You want the substance feature set and don't need the biggest community
- You prefer the MIT license terms
- Your stack matches JavaScript
- You evaluated both and substance fits your workflow better
About readest
Readest [Readest][link website] is an open source ebook reader designed for immersive and deep reading experiences. Built as a modern rewrite of Foliate, it leverages Next.js 16 and Tauri v2 to deliver a smooth, cross platform experience across macOS, Windows, Linux, Android, iOS, and the Web. [![Website][badge website]][link website] [![Web App][badge web app]][link web readest] [![OS][badge platforms]][link website] [![Discord][badge discord]][link discord] [![Reddit][badge reddit]][link reddit] [![AGPL Licence][badge license]](LICENSE) [![Language Coverage][badge language coverage]][link locales]…
read the full readest overview →
About substance
Substance.js Substance is a JavaScript library for web based content editing. It provides building blocks for realizing custom text editors and web based publishing system. It is developed to power our online editing platform Substance. Development Install the dev dependencies. Run the dev server. Navigate to for the running the browser test suite. The test suite is rebuilt as you make changes to the source files. To run the test suite headless.
read the full substance overview →
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Frequently asked questions
Is readest or substance more popular?
readest has 25,874 GitHub stars and substance has 2,738. readest has the larger community by that measure.
Are readest and substance free?
Both are open source. readest is licensed under AGPL-3.0 and substance under MIT. Neither carries a licence fee.
What is the difference between readest and substance?
readest is written in TypeScript and substance in JavaScript. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, readest or substance?
Choose readest if you want the larger community (25,874 stars) or its AGPL-3.0 licence terms. Choose substance if its feature set, stack or MIT licence fits better. Both are self-hostable.