EPUB Ninja - eBook Reader by Digital Fracture
A fast, lightweight EPUB and CBZ reader in your browser sidebar. Import books and comics, pick up where you left off, and read without distractions. 100% local your files never leave your browser.
Some features may require paymentSome features may require payment
Available on Firefox for Android™Available on Firefox for Android™
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About this extension
EPUB Ninja is a clean, distraction-free eBook and comic reader that lives in your Firefox sidebar. Import your EPUB and CBZ files, and start reading no cloud, no tracking.
FEATURES
• Sidebar eBook Reader: Read EPUBs right inside Firefox. No separate app needed.
• CBZ Comic Support: Import comic book archives with single page, two-page spread, and fullscreen viewing modes.
• Book Library: Manage your collection with cover art, reading progress, and sort by recent, title, or progress.
• Dark & Light Themes: Full dark mode that themes the entire browser chrome to match.
• Table of Contents: Slide-out chapter navigation. Jump to any section instantly.
• Bookmarks: Bookmark any chapter and return to it with one click.
• Full-Text Search: Search across every chapter of your book.
• Reader Settings: Font size, font family, line height, margins, text alignment, and paragraph spacing.
• Keyboard Navigation: Arrow keys to navigate, F for fullscreen, 1/2 for page modes, Escape to close panels.
• Reading Progress: Automatically saved. Close the browser and pick up exactly where you left off.
• 100% Local: All data stored in your browser. Books never leave your device. No servers, no uploads, no tracking.
SUPPORTED FORMATS
• EPUB 2 and EPUB 3 (eBooks)
• CBZ (Comic Book ZIP archives)
HOW IT WORKS
Your books are stored locally in IndexedDB and browser storage. Nothing is sent anywhere.
Part of the Ninja suite from the makers of RSS Ninja.
Website: https://rssninja.co.uk
FEATURES
• Sidebar eBook Reader: Read EPUBs right inside Firefox. No separate app needed.
• CBZ Comic Support: Import comic book archives with single page, two-page spread, and fullscreen viewing modes.
• Book Library: Manage your collection with cover art, reading progress, and sort by recent, title, or progress.
• Dark & Light Themes: Full dark mode that themes the entire browser chrome to match.
• Table of Contents: Slide-out chapter navigation. Jump to any section instantly.
• Bookmarks: Bookmark any chapter and return to it with one click.
• Full-Text Search: Search across every chapter of your book.
• Reader Settings: Font size, font family, line height, margins, text alignment, and paragraph spacing.
• Keyboard Navigation: Arrow keys to navigate, F for fullscreen, 1/2 for page modes, Escape to close panels.
• Reading Progress: Automatically saved. Close the browser and pick up exactly where you left off.
• 100% Local: All data stored in your browser. Books never leave your device. No servers, no uploads, no tracking.
SUPPORTED FORMATS
• EPUB 2 and EPUB 3 (eBooks)
• CBZ (Comic Book ZIP archives)
HOW IT WORKS
- Click the EPUB Ninja icon in your toolbar to open the sidebar.
- Click "Import EPUB / CBZ" and select your files.
- Click a book to start reading.
Your books are stored locally in IndexedDB and browser storage. Nothing is sent anywhere.
Part of the Ninja suite from the makers of RSS Ninja.
Website: https://rssninja.co.uk
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Permissions and data
Required permissions:
- Access browser tabs
Optional permissions:
- Access your data for rssninja.co.uk
Data collection:
- The developer says this extension doesn't require data collection.
More information
- Add-on Links
- Version
- 1.0.2
- Size
- 1.38 MB
- Last updated
- 8 days ago (Apr 6, 2026)
- Related Categories
- License
- Mozilla Public License 2.0
- Privacy Policy
- Read the privacy policy for this add-on
- Version History
- Add to collection