What is an EPUB file?

EPUB (Electronic Publication) is the most widely used open standard format for digital books and publications. Developed by the International Digital Publishing Forum (IDPF), EPUB files use a combination of HTML, CSS, and XML to create reflowable content that automatically adapts to different screen sizes and reading preferences. Unlike fixed-format PDFs, EPUB books adjust their layout based on the reader's device, font size choices, and display settings.

The EPUB format has become the industry standard for e-books because it offers exceptional flexibility for both publishers and readers. Major retailers including Apple Books, Google Play Books, and Kobo use EPUB as their primary format. The format supports rich features like embedded images, table of contents navigation, metadata (author, title, publisher), and styled text formatting. EPUB 3, the latest version, adds support for multimedia content, JavaScript interactivity, and improved accessibility features.

Tool description

A free online EPUB reader that lets you open and read EPUB books directly in your browser without installing any software. Simply drag and drop your EPUB file or click to upload, and start reading immediately. The reader provides a comfortable reading experience with customizable font sizes, chapter navigation, and a built-in table of contents sidebar for easy book navigation.

Examples

Supported file: Any valid .epub file (EPUB 2 or EPUB 3 format)

Reading experience includes:

  • Full chapter content with original formatting preserved
  • Embedded images displayed inline
  • Clickable table of contents for quick navigation
  • Previous/next chapter navigation buttons

Features

  • Browser-based reading: Read EPUB books instantly without downloading or installing any e-reader software
  • Drag and drop upload: Simply drag your EPUB file onto the reader or click to browse and select
  • Table of contents navigation: Access the book's table of contents from a convenient sidebar to jump to any chapter
  • Adjustable font size: Increase or decrease text size for comfortable reading on any screen
  • Chapter navigation: Navigate between chapters using previous/next buttons or the table of contents
  • Image support: View embedded book illustrations and cover images as intended by the publisher
  • Fullscreen mode: Expand the reader to fullscreen for distraction-free reading
  • Resizable reader area: Drag the bottom edge to adjust the reader height to your preference
  • Privacy-focused: Your books never leave your device—all processing happens locally in your browser
  • Metadata display: View book title, author, and other publication information

Use cases

  • Quick book preview: Open and preview EPUB books before transferring them to your dedicated e-reader device
  • Cross-platform reading: Read your EPUB collection on any computer with a web browser, regardless of operating system
  • No-install solution: Read e-books on work computers, public terminals, or borrowed devices where you cannot install software

Supported formats

  • EPUB 2: The widely supported standard format used by most e-book publishers
  • EPUB 3: The newer format with enhanced features including improved styling and multimedia support
  • File extension: .epub
  • MIME type: application/epub+zip

How it works

When you upload an EPUB file, the reader extracts the compressed archive containing the book's content. It parses the package document (OPF file) to identify the book's structure, metadata, and reading order. The table of contents is extracted from the navigation document (NCX or NAV), and each chapter's HTML content is rendered with its associated styles. All processing happens entirely in your browser—your book files are never uploaded to any server.

Limitations

  • DRM-protected books: Books with Digital Rights Management (DRM) encryption cannot be opened
  • Complex layouts: Some books with highly complex fixed layouts may not render exactly as intended
  • Multimedia content: Audio and video embedded in EPUB 3 books are not currently supported
  • Reading progress: Your reading position is not saved between sessions

Tips

  • Use the fullscreen button for an immersive, distraction-free reading experience
  • Adjust the font size before starting to read for optimal comfort
  • Use the table of contents sidebar to quickly navigate to specific chapters or sections
  • Drag the resize handle at the bottom of the reader to customize the viewing area height

FAQ

Is my book uploaded to a server? No. All processing happens locally in your browser. Your EPUB files never leave your device, ensuring complete privacy.

Why can't I open my purchased e-book? Most e-books purchased from major retailers (Amazon, Barnes & Noble) use DRM protection that prevents them from being opened in third-party readers. This tool only works with DRM-free EPUB files.

Can I read Amazon Kindle books? No. Kindle books use Amazon's proprietary AZW/KF8 format, not EPUB. You would need to convert them to EPUB first using a tool like Calibre (only possible for DRM-free books).