head to head · open source
koodo-reader vs substance
koodo-reader has 28,217 GitHub stars, 2,116 forks, 271 open issues and last shipped yesterday. substance has 2,733 stars, 121 forks, 41 open issues and last shipped 6 months ago. koodo-reader leads on adoption by 932% (28,217 vs 2,733 stars). koodo-reader is written in JavaScript under AGPL-3.0; substance is written in JavaScript under MIT. koodo-reader has attracted 7% as many forks as stars, substance 4%. koodo-reader was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 1 topic tag (html), 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
| koodo-reader | substance | |
|---|---|---|
| GitHub stars | ★ 28K | ★ 2.7K |
| License | AGPL-3.0 | MIT |
| Written in | JavaScript | JavaScript |
| Last push | 2026-09-17 | 2026-04-02 |
| Forks | ⑂ 2.1K | ⑂ 121 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick koodo-reader if
- You weight community size — 28K stars and counting
- You want the AGPL-3.0 license terms
- Your stack matches JavaScript
- 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 koodo-reader
Koodo Reader is a cross platform ebook manager and reader written in JavaScript and released under the AGPL 3.0 license. It runs on Windows, macOS, Linux, Android, iOS, and the web, and it is distributed both as downloadable desktop and mobile applications and as a hosted web version at web.koodoreader.com. The project lives in the JavaScript ecosystem, is developed with yarn and git, and has been maintained for roughly seven years, with a repository that carries about 28,000 stars and 2,100 forks.
read the full koodo-reader overview →
About substance
Substance is a JavaScript library for web based content editing. It lives in the JavaScript and Content & Publishing / Publishing ecosystem, and it is distributed under the MIT license. The README describes it as a library that provides building blocks for realizing custom text editors and web based publishing systems, and it was developed to power the online editing platform Substance.
read the full substance overview →
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Frequently asked questions
Is koodo-reader or substance more popular?
koodo-reader has 28,217 GitHub stars and substance has 2,733. koodo-reader has the larger community by that measure.
Are koodo-reader and substance free?
Both are open source. koodo-reader is licensed under AGPL-3.0 and substance under MIT. Neither carries a licence fee.
What is the difference between koodo-reader and substance?
koodo-reader is written in JavaScript 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, koodo-reader or substance?
Choose koodo-reader if you want the larger community (28,217 stars) or its AGPL-3.0 licence terms. Choose substance if its feature set, stack or MIT licence fits better. Both are self-hostable.