Epubespiar - EPUB Reader

A powerful browser extension for reading EPUB books directly in your browser with a beautiful library management system.

Features

📖 Enhanced Reader

• Seamless Reading: Read EPUB books with a clean, distraction-free interface
• Smart Navigation: Easy switching between the library and the reader
• Table of Contents: Quick navigation through chapters and sections
• Zoom Controls: Adjust view widths for comfortable reading
• Font Controls: Adjust text size for comfortable reading
• Responsive Design: Works great on desktop and mobile devices
• Epub URL Intercepts: toggle on and off to open epub books automatically from URLs
• Progress Tracking: Through percentage

🎯 Smart Interactions

• Drag & Drop: Drop EPUB files onto the reader to open immediately and add to the library

Get the extension

Firefox	Edge	Chrome

Getting Started

Epubespiar.quick.start.mp4

Architecture

EPUB opening currently follows two real paths:

1. Normal-page drag/drop path (content script available)
   Drag an EPUB URL onto a regular web page where src/content/epub-handler.js runs.
2. Browser download path (content script unavailable, e.g. chrome://newtab)
   In built-in pages like New Tab, content scripts cannot run, so Chrome's normal navigation/download flow happens and the extension reacts through Downloads API listeners in src/background/index.js.

Technical Stack

• Vue 3: Modern reactive framework for UI
• jszip.js: EPUB parsing and rendering
• CSS3 & SCSS: For great styling
• Vite: Fast build tool and development server
• Manifest V3: Latest Chrome extension API

Development

# Install dependencies
pnpm install

# Development mode
pnpm run dev

# Build for Chrome
pnpm run build:chrome

# Build for Firefox
pnpm run build:firefox

# Build all
pnpm run build

Usage

Instant Reading (EPUB Opening Flows)

The extension automatically intercepts EPUB files anywhere in your browser, just like how browsers handle PDFs:

Note

The full functionality is only available on Chromium browsers since firefox based browsers does not support drag-and-drop local files with the help of an extension, as it does for videos, images, or PDF files

1) Normal-page drag/drop flow

When drag/drop happens on a normal page where the content script runs:

• src/content/epub-handler.js reads dragged data from text/uri-list or text/plain.
• It validates only https: and file: URLs that end in .epub.
• On a valid drop, it prevents default browser drop behavior and sends EPUB_DROP to the background script.
• src/background/index.js validates again, then opens:
  • reader.html?file=<encoded-epub-url>&instance=<id>

2) Download interception flow

When content scripts cannot run (for example chrome://newtab) or when browser download behavior is used:

• src/background/index.js listens on browser.downloads.onCreated and browser.downloads.onChanged.
• It detects EPUB candidates using URL, filename, or MIME type (application/epub+zip).
• Local file EPUBs (file://...): it cancels and erases the download, then opens the reader with the original file:// URL.
• HTTPS downloads: interception is only enabled when storage.local.interceptDownloads === true.

This is not a hidden chrome://newtab file-drop API. It relies on normal Chrome navigation/download behavior plus the extension's Downloads API listeners.

3) Reader flow

Both paths end by opening the extension reader with:

• reader.html?file=<encoded-epub-url>

Use cases?

• Use Entry Point 2 when:
  • You find an EPUB on a website and want to read it immediately
  • You're continuing a book you've already started
  • You receive an EPUB file and want quick access
  • You want the book to open automatically (like PDFs)

Features in Detail

Reader Page

• Header toolbar with navigation controls
• Sidebar with table of contents
• Main reading area with EPUB content
• Zoom controls for text size

Browser Compatibility

• Chrome/Edge: Full support
• Firefox: Full support
• Other Chromium-based browsers: Should work with the Chrome build

What's not implemented

• Epub book library
• Download status: This shows the progress of your download
• What you thought was, but is not, while using the extension