head to head · open source
calibre vs kokoro-tts
calibre has 26,327 GitHub stars, 2,743 forks, 6 open issues and last shipped yesterday. kokoro-tts has 1,978 stars, 180 forks, 17 open issues and last shipped 2 months ago. calibre leads on adoption by 1,231% (26,327 vs 1,978 stars). calibre is written in Python under GPL-3.0; kokoro-tts is written in Python under MIT. calibre has attracted 10% as many forks as stars, kokoro-tts 9%. calibre was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 2 topic tags (epub, python), 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
| calibre | kokoro-tts | |
|---|---|---|
| GitHub stars | ★ 26K | ★ 2.0K |
| License | GPL-3.0 | MIT |
| Written in | Python | Python |
| Last push | 2026-11-02 | 2026-08-22 |
| Forks | ⑂ 2.7K | ⑂ 180 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick calibre if
- You weight community size — 26K stars and counting
- You want the GPL-3.0 license terms
- Your stack matches Python
- You value the larger contributor base for long-term maintenance
pick kokoro-tts if
- You want the kokoro-tts feature set and don't need the biggest community
- You prefer the MIT license terms
- Your stack matches Python
- You evaluated both and kokoro-tts fits your workflow better
About calibre
calibre calibre is an e book manager. It can view, convert, edit and catalog e books in all of the major e book formats. It can also talk to e book reader devices. It can go out to the internet and fetch metadata for your books. It can download newspapers and convert them into e books for convenient reading. It is cross platform, running on Linux, Windows and macOS. For more information, see the calibre About page. Screenshots Screenshots page Usage See the User Manual. Development Setting up a development environment for calibre. A tarball of the source code for the current calibre release. Bugs Bug reports and…
read the full calibre overview →
About kokoro-tts
Kokoro TTS A CLI text to speech tool using the Kokoro model, supporting multiple languages, voices (with blending), and various input formats including EPUB books and PDF documents. Features Multiple language and voice support Voice blending with customizable weights EPUB, PDF and TXT file input support Standard input (stdin) and piping from other programs Streaming audio playback Split output into chapters Adjustable speech speed WAV and MP3 output formats Chapter merging capability Detailed debug output option GPU Support Demo Kokoro TTS is an open source CLI tool that delivers high quality text to speech…
read the full kokoro-tts overview →
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Frequently asked questions
Is calibre or kokoro-tts more popular?
calibre has 26,327 GitHub stars and kokoro-tts has 1,978. calibre has the larger community by that measure.
Are calibre and kokoro-tts free?
Both are open source. calibre is licensed under GPL-3.0 and kokoro-tts under MIT. Neither carries a licence fee.
What is the difference between calibre and kokoro-tts?
calibre is written in Python and kokoro-tts in Python. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, calibre or kokoro-tts?
Choose calibre if you want the larger community (26,327 stars) or its GPL-3.0 licence terms. Choose kokoro-tts if its feature set, stack or MIT licence fits better. Both are self-hostable.