head to head · open source
calibre vs WritingTools
calibre has 26,327 GitHub stars, 2,743 forks, 6 open issues and last shipped yesterday. WritingTools has 2,479 stars, 165 forks, 79 open issues and last shipped 3 months ago. calibre leads on adoption by 962% (26,327 vs 2,479 stars). calibre is written in Python under GPL-3.0; WritingTools is written in Swift under GPL-3.0. calibre has attracted 10% as many forks as stars, WritingTools 7%. calibre 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
| calibre | WritingTools | |
|---|---|---|
| GitHub stars | ★ 26K | ★ 2.5K |
| License | GPL-3.0 | GPL-3.0 |
| Written in | Python | Swift |
| Last push | 2026-11-02 | 2026-08-19 |
| Forks | ⑂ 2.7K | ⑂ 165 |
| 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 WritingTools if
- You want the WritingTools feature set and don't need the biggest community
- You prefer the GPL-3.0 license terms
- Your stack matches Swift
- You evaluated both and WritingTools 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 WritingTools
Writing Tools 🍎 Using a Mac? Jump to the macOS (Native Swift Port) section → macOS Instantly proofread and optimize your writing system wide with AI: Summarize content (webpages, YouTube videos, documents...) in a click: Add your own buttons for unlimited potential! ✨ What is Writing Tools? Writing Tools is an Apple Intelligence inspired application for Windows, Linux, and macOS that supercharges your writing with an AI LLM (cloud based or local). With one hotkey press system wide, it lets you fix grammar, optimize text according to your instructions, summarize content (webpages, YouTube videos, etc.), and…
read the full WritingTools overview →
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Frequently asked questions
Is calibre or WritingTools more popular?
calibre has 26,327 GitHub stars and WritingTools has 2,479. calibre has the larger community by that measure.
Are calibre and WritingTools free?
Both are open source. calibre is licensed under GPL-3.0 and WritingTools under GPL-3.0. Neither carries a licence fee.
What is the difference between calibre and WritingTools?
calibre is written in Python and WritingTools in Swift. 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 WritingTools?
Choose calibre if you want the larger community (26,327 stars) or its GPL-3.0 licence terms. Choose WritingTools if its feature set, stack or GPL-3.0 licence fits better. Both are self-hostable.