Calibre
Powerful, open-source ebook manager with conversion, library, and editing tools.
Open the official app on calibre-ebook.com
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Self-host it
Run the open-source version on your own infrastructure.
What is Calibre?
Calibre is an open-source e-book management tool designed to organize, convert, and synchronize digital books across devices. It serves as a centralized platform for users to catalog their e-book collections, edit metadata, and transform files between formats like EPUB, MOBI, and PDF. Targeted at avid readers, librarians, and content creators, Calibre addresses the challenge of managing diverse e-book formats and ensuring compatibility with various e-readers. By automating tasks such as metadata retrieval and format conversion, it streamlines workflows for users who need to maintain a cohesive library while adapting content for different devices. The tool's cross-platform support for Linux, Windows, and macOS ensures broad accessibility. Its ability to fetch metadata from the internet enhances library organization, while integration with e-reader hardware simplifies synchronization. Calibre's active development community, reflected in its 25.6k GitHub stars, underscores its reliability and adaptability. Users benefit from a balance of simplicity and advanced features, making it suitable for both casual readers and technical users requiring customization.
How it works
Calibre is an open-source e-book manager that consolidates tasks like viewing, converting, editing, and organizing e-books into a single interface. It enables users to manage their digital libraries efficiently, ensuring compatibility with popular e-reader devices and formats. The tool's primary purpose is to resolve the fragmentation of e-book formats by providing conversion between EPUB, MOBI, PDF, and other supported types. It also automates metadata collection, enhancing library organization without manual input. Calibre supports format conversion between EPUB, MOBI, PDF, and others, with tools like 'Convert Books' enabling batch processing. It integrates with e-readers via USB or cloud services, allowing direct device synchronization. The 'Fetch Metadata' feature automatically retrieves book details from the internet, improving catalog accuracy.
How to use it
- 1Download and install Calibre from its official website or package managers. 2. Launch the application and import e-books by dragging files into the library or using the 'Add Books' button. 3. Use the 'Convert Books' tool to change formats, selecting target types and customization options. 4. Sync the library with e-readers via USB or cloud services like Dropbox. Practical tips include organizing books into folders for metadata editing, utilizing the 'Fetch Metadata' feature for automatic updates, and leveraging the web interface for remote access. Regular backups and plugin updates ensure long-term usability.
What it can do
- ebook management
Use cases
Assumptions and limitations
Assumptions
- source: https://github.com/kovidgoyal/calibre
- license: GPL-3.0 — free to use
- privacy: Self-hosted — you control your data
Limitations
- Limited support for complex PDFs with embedded fonts or encryption
- Conversion quality may vary for scanned images or non-standard layouts
- No built-in DRM removal capabilities for protected content
- Requires manual setup for advanced customization options
- Lacks native support for some modern e-reader formats like AZW3
Understanding the result
Powerful, open-source ebook manager with conversion, library, and editing tools.
Tool details
- Clearly flagged when a network request is needed.
- No account, no sign-up, and no tracking of your content.
- Powered by (GPL-3.0).
- Built with
- (kovidgoyal/calibre)
- License
- GPL-3.0
- Runs locally
- No — requires a network request
- Verification
- Not yet verified
- Input
- Query
- Output
- Text
Built with kovidgoyal/calibre. OpenToolVault provides the discovery and browser interface while crediting the original project maintainers.
- Built with
- License
- GPL-3.0
Open-source project
OpenToolVault is an independent directory. We are not affiliated with or endorsed by this project.
References
- / — GitHub Repository
Upstream project · GitHub
- GPL-3.0 License
Upstream project
Frequently asked
How does Calibre handle e-book format conversion?
Calibre uses internal libraries and external tools to convert between formats. For example, PDF to EPUB conversion relies on OCR for scanned documents, while text-based formats use direct reflow. Users can customize conversion settings like margins and fonts through the 'Format' options in the Convert Books tool.
How does Calibre synchronize with e-readers?
Calibre communicates with e-readers via USB connections or cloud services. When connected, it detects supported devices and offers options to sync the entire library or select titles. For Kindle devices, it uses the Amazon Cloud Drive API to transfer books, while Kobo devices sync through their proprietary protocol.
How do I convert a scanned PDF to EPUB?
1. Import the PDF into Calibre's library. 2. Right-click the file and select 'Convert Books'. 3. Choose EPUB as the output format. 4. Enable the 'OCR' option under the 'Conversion' tab. 5. Adjust layout settings like page margins and text spacing. 6. Export the converted file and verify readability.
How does Calibre compare to alternatives like FBReader or KOReader?
Calibre focuses on library management and format conversion, while FBReader and KOReader are primarily e-readers with limited editing capabilities. Calibre's strength lies in its comprehensive toolset for managing multi-format libraries, whereas FBReader offers better text rendering for complex documents. KOReader provides advanced annotation features but lacks Calibre's conversion capabilities.
What should I do if conversion fails with a 'Format Not Supported' error?
First, verify the file is not corrupted by opening it in a text editor. Check Calibre's format support list to confirm compatibility. For PDFs, ensure the file isn't encrypted or contains non-text layers. Use the 'Verify' function in Calibre to check file integrity. If needed, try converting to a different format first before attempting the original target.