ChunkFlow - Parallel Download & Upload Chrome Extension

Version: 2.3.0
Manifest version: 3

🚀 Overview

ChunkFlow is a powerful Chrome extension that accelerates downloads and uploads by splitting files into chunks and processing them in parallel. When servers support HTTP range requests, ChunkFlow can significantly speed up file transfers by downloading/uploading multiple chunks simultaneously, then seamlessly merging them back together.

⚡ Key Features

🔽 Smart Download Management

• Parallel chunked downloads - Automatically detects server support for range requests and downloads files in chunks for faster speeds
• Intelligent fallback - Seamlessly falls back to regular downloads when chunking isn't supported
• Universal link detection - Works with any download link (not just those with download attribute)
• Real-time progress tracking - Live progress bars with file size information
• Download controls - Pause, resume, restart, and delete downloads
• Context menu integration - Right-click any link to download with ChunkFlow

📤 Advanced Upload Capabilities

• Chunked uploads - Split large files into chunks for parallel upload to compatible servers
• Upload testing - Test server chunked upload capabilities
• File preview - Image preview before uploading
• Upload history - Track previously uploaded files with metadata
• Progress monitoring - Real-time upload progress for each chunk

🎨 Modern Interface

• Clean, responsive UI - Modern design with smooth animations
• Tabbed interface - Separate Downloads and Uploads sections
• Real-time updates - Dynamic refresh rates based on activity
• Status indicators - Clear visual feedback for all operations
• File size formatting - Human-readable file sizes and timestamps

🏗️ Architecture

Background Service Worker (background.js)

• Download engine: Implements downloadInChunks() with HEAD request validation, parallel fetch operations, and chunk merging
• Upload engine: Handles both normal and chunked uploads with server compatibility detection
• Chrome Downloads API integration: Manages pause/resume/restart/delete operations
• Storage management: Persists upload history to chrome.storage.local
• Event-driven updates: Real-time communication with popup via ports

Content Script (contentScript.js)

• Smart link detection: Identifies download links by file extension and download attribute
• Dynamic handler attachment: Uses MutationObserver to handle dynamically added links
• URL validation: Prevents invalid download attempts
• Context menu support: Enables right-click download functionality

Popup Interface (popup.html, popup.css, popup.js)

• Dual-tab layout: Downloads management and Upload testing
• Live progress tracking: Real-time download progress with adaptive update frequency
• File management: Upload file selection, preview, and history
• Error handling: User-friendly error messages and validation
• Responsive design: Modern, mobile-friendly interface

Utilities (utils.js)

• File size formatting: Human-readable byte conversion
• URL validation: Robust URL checking
• Filename sanitization: Safe filename handling
• File type detection: Smart file extension and MIME type handling
• Utility functions: Debouncing, timestamps, and helper methods

🔧 Technical Implementation

Chunked Download Process

1. HEAD request to check Accept-Ranges: bytes header
2. Parallel fetching of byte ranges (default: 10 chunks)
3. Chunk validation and error handling per segment
4. Memory-efficient merging into single Uint8Array
5. Blob creation and automatic download trigger

Chunked Upload Process

1. Server compatibility check via HEAD request
2. File chunking with configurable chunk count
3. Parallel upload using XMLHttpRequest with Content-Range headers
4. Progress tracking per chunk with aggregated reporting
5. Fallback to normal upload if chunking unsupported

Performance Optimizations

• Adaptive polling: Faster updates during active downloads (500ms), slower when idle (2s)
• Event-driven updates: Chrome Downloads API events trigger immediate UI refreshes
• Memory management: Efficient chunk assembly with proper cleanup
• Error resilience: Robust fallback mechanisms for network issues

📋 Permissions & Security

• downloads: Manage Chrome downloads
• storage: Persist upload history
• contextMenus: Right-click download options
• <all_urls>: Detect download links on any website
• Optional management: Extension management features

🚀 Installation & Usage

Installation

1. Download the extension files
2. Open chrome://extensions/
3. Enable "Developer mode"
4. Click "Load unpacked" and select the extension folder
5. The ChunkFlow icon will appear in your browser toolbar

Using Downloads

• Method 1: Click any download link - ChunkFlow automatically intercepts and accelerates it
• Method 2: Right-click any link → "Download with ChunkFlow"
• Monitor progress: Click the ChunkFlow icon to see real-time download progress
• Manage downloads: Use pause/resume/restart/delete controls in the popup

Using Uploads (Testing)

1. Click the ChunkFlow icon → Switch to "Uploads" tab
2. Enter a server URL that accepts file uploads
3. Select a file using "Select File" button
4. Click "Upload File" to start chunked upload
5. View upload history and progress

🔍 Server Requirements

For Chunked Downloads

• Server must return Accept-Ranges: bytes header
• Must support HTTP Range requests (Range: bytes=start-end)
• Must return proper Content-Length header

For Chunked Uploads

• Server must accept Content-Range headers
• Must support partial content uploads
• Should handle multiple concurrent POST requests

🎯 Performance Benefits

Download Speed Improvements

• 2-5x faster on supported servers with good bandwidth
• Better reliability on unstable connections (chunk-level retry)
• Resume capability for interrupted downloads
• Memory efficient chunk processing

Upload Speed Improvements

• Parallel upload streams for faster large file transfers
• Progress granularity with per-chunk reporting
• Automatic fallback for unsupported servers
• Error isolation per chunk

🔧 Configuration

• Default chunks: 10 parallel streams (configurable in code)
• Update frequency: 500ms active, 2s idle
• File detection: Automatic by extension
• Memory usage: Optimized for large files

📝 Technical Notes

• Chunk merging: Uses Uint8Array for efficient memory handling
• URL validation: Prevents malformed download attempts
• Dynamic link handling: Automatically detects new download links on pages
• Cross-platform: Works on all Chrome-supported operating systems
• Extension API: Full Chrome Downloads API integration

🐛 Known Limitations

• Server dependency: Chunking requires server-side range request support
• Memory usage: Large files are assembled in memory during merge
• File messaging: Upload files converted to ArrayBuffer for background processing
• Update polling: Some UI updates still use polling vs pure event-driven
• Filename parsing: Uses URL path, doesn't parse Content-Disposition headers

🔮 Future Roadmap

• Stream processing: Reduce memory usage for very large files
• Smart chunk sizing: Dynamic chunk count based on file size and connection speed
• Content-Disposition parsing: Better filename detection from HTTP headers
• Upload progress UI: Real-time chunk-level upload progress visualization
• Configuration panel: User-configurable chunk settings
• Download queue: Batch download management with priority controls
• Bandwidth throttling: Optional speed limiting for chunked transfers