head to head · open source
calibre vs grimmory
calibre has 26,327 GitHub stars, 2,743 forks, 6 open issues and last shipped yesterday. grimmory has 4,642 stars, 357 forks, 243 open issues and last shipped yesterday. calibre leads on adoption by 467% (26,327 vs 4,642 stars). calibre is written in Python under GPL-3.0; grimmory is written in Java under AGPL-3.0. calibre has attracted 10% as many forks as stars, grimmory 8%. grimmory was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 2 topic tags (ebooks, epub), 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 | grimmory | |
|---|---|---|
| GitHub stars | ★ 26K | ★ 4.6K |
| License | GPL-3.0 | AGPL-3.0 |
| Written in | Python | Java |
| Last push | 2026-11-02 | 2026-11-02 |
| Forks | ⑂ 2.7K | ⑂ 357 |
| 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 grimmory if
- You want the grimmory feature set and don't need the biggest community
- You prefer the AGPL-3.0 license terms
- Your stack matches Java
- You evaluated both and grimmory 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 grimmory
Grimmory is a self hosted digital library for people who take their reading seriously. Documentation · Quick Start · Translations · Discord · Releases Features Supported Formats Quick Start [!TIP] For OIDC setup, advanced configuration, or upgrade guides, see the full documentation. Requirements: Docker and Docker Compose. Image Repositories Step 1: Environment Configuration Create a .env file: Step 2: Docker Compose Stable images are published from semantic release tags on main as vX.Y.Z plus latest . Nightly images are built from develop and tagged nightly . Create a docker compose.yml or copy and adapt…
read the full grimmory overview →
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Frequently asked questions
Is calibre or grimmory more popular?
calibre has 26,327 GitHub stars and grimmory has 4,642. calibre has the larger community by that measure.
Are calibre and grimmory free?
Both are open source. calibre is licensed under GPL-3.0 and grimmory under AGPL-3.0. Neither carries a licence fee.
What is the difference between calibre and grimmory?
calibre is written in Python and grimmory in Java. 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 grimmory?
Choose calibre if you want the larger community (26,327 stars) or its GPL-3.0 licence terms. Choose grimmory if its feature set, stack or AGPL-3.0 licence fits better. Both are self-hostable.