calibre - E-book management | WarmIndex

Calibre is a free and open-source e-book management application that lets users organize, convert, view, edit, and sync e-books across devices, built for book lovers of all levels.

🚀 Overview

Calibre is a powerful, cross-platform e-book manager designed to handle every aspect of your digital book collection. From organizing thousands of books with intuitive metadata management to converting between dozens of formats and editing EPUB or Kindle files directly, it streamlines the entire e-book workflow. It also includes a built-in viewer, device syncing, news-to-ebook downloads, and a content server for sharing your library anywhere.

What problem does this project solve?

Disorganized e-book libraries, incompatible formats across devices, tedious metadata entry, and lack of editing tools in standard software.

Who is it built for?

Book lovers, casual readers building personal libraries, power users editing books, and anyone managing e-books on desktop or mobile.

Why did you build it? Calibre was created by book lovers for book lovers to go beyond basic e-book software, providing a complete, free solution that's been refined over 15+ years with community input.

✨ Key Features

Library Management: Intuitive interface with customizable views (covers, tags, authors), advanced search/sort, metadata download/edit, and tracking of read/liked books.
Format Conversion: Converts dozens of input formats to optimal device formats, fixes layout issues, adds TOC, and handles personal docs.
Device Syncing: Supports nearly all e-readers/tablets, auto-converts/sends books via USB or wireless.
Editing & Viewing: Built-in editor for EPUB/AZW3/Kindle, viewer with highlights/bookmarks/read-aloud, annotations browser.
News & Sharing: Downloads from 100s of sources/RSS into e-books; content server for browser access anywhere; plugins for extensibility.
Upcoming: Continued improvements like reading progress columns, image cleanup tools (v9.5).

🛠 Tech Stack

Language: Python 3.8+
GUI: PyQt / Qt
Other: Some C/C++ for performance; modular with plugins
Platforms: Windows, macOS, Linux, Portable USB, Android companion
Database: Internal (SQLite for library metadata)

👥 Who Is This For?

This project is useful for:

Book lovers managing large personal e-book collections
Readers needing format conversion and device compatibility
E-book enthusiasts editing metadata or content directly
Users wanting automated news/magazine downloads as e-books

📸 Screenshots / Demo

Video demo: https://calibre-ebook.com/demo
GitHub: https://github.com/kovidgoyal/calibre
Downloads: https://calibre-ebook.com/download

🔥 Project Status

🟢 Actively building

Last updated: 2026-03-24

❓ FAQ

Is this project free?

Yes — Completely free and open source (GPL licensed). (Over 3 million active installs.)

Is the source code available?

Yes — https://github.com/kovidgoyal/calibre

Can I contribute?

Yes — Fork the repo, build from source (see manual.calibre-ebook.com/develop.html), submit PRs. Report bugs or get help on the MobileRead forum; translations via Get Involved page; develop plugins.