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What is CyberViewer?

CyberViewer is a fast, lightweight image and video viewer for Windows that covers everyday viewing and editing without the weight of a full graphics suite. Open large images quickly, browse complete folders through a thumbnail sidebar, zoom and pan smoothly, run slideshows, and manage recent files. Essential tools for rotation, cropping, resizing, flipping, and color adjustment are built in, alongside wallpaper controls and Windows Explorer integration. The interface stays focused, dark, and highly customizable. Built with Electron 35 and vanilla JavaScript.

Free and open source (GPLv3). CyberViewer adds no advertising or analytics. Optional YouTube playback connects to YouTube and uses its official player.

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🎯 Why CyberViewer?

Most image viewers are either bloated with features you never use or so barebones they feel like an afterthought. CyberViewer strikes the perfect balance: instant loading, smooth browsing, and essential editing tools, all wrapped in a sleek, distraction-free interface.

Need	Solution
Open images instantly	Streaming cvlocal:// protocol with no full RAM load, even for large files
Browse a whole folder	Thumbnail sidebar with lazy loading and radar scan progress
Quick edits without Photoshop	Rotate, crop, resize, flip, adjust brightness/contrast/saturation/blur
Immersive viewing	Fullscreen mode with auto-hiding UI, slideshow with loop
Set the desktop wallpaper	Fill, Fit, Center, or Span the current image across Windows
Stay in your workflow	System tray, recent images, auto-start, global hotkey, Explorer context menu
Bilingual (EN / ES)	Complete UI localization with instant language switching

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✨ Key Features

🖼️ Viewing

• Image tabs: open multiple files together, reorder tabs, search by name or path, and reopen closed tabs. Each tab keeps its zoom, pan, and pending rotation. Folder navigation stays in the current tab; use the thumbnail context menu or middle-click to open another tab. A tab with unsaved changes stays open when navigating to another image.
• Optional session restore: enable Configuration → General → Restore previous session to recover tab order, the active image, views, pending rotations, and pasted images after restarting. Missing files stay in their tabs and can be located again. Session data stays local and separate from settings backups; disabling the option removes the saved session.
• Lightning-fast open: custom streaming protocol loads images without hogging RAM
• Supported formats: JPG, JPEG, PNG, GIF, WebP, BMP, TIFF, TIF, ICO, and AVIF
• Folder browsing: thumbnail sidebar with lazy loading, priority queue, and scan progress indicator
• Zoom and pan: 5% to 2000%, fit-to-window, original size (1:1), mouse wheel, and drag
• Animated GIF support: toggle playback on or off
• Fullscreen immersive mode: ghost UI auto-hides for distraction-free viewing
• Drag and drop: drop images or folders directly onto the window
• Clipboard paste: paste images from the clipboard (Ctrl+V)

▶️ Video playback

• Open MP4, M4V, WebM, MOV, and MKV through the file picker, drag and drop, folder navigation, or tabs. Support depends on the video and audio codecs inside each file and the computer's decoder capabilities.
• Play/pause, seek, adjust volume, mute, and loop. Videos play automatically on open by default; turn Autoplay on open off in the … menu for manual playback. The preference is saved. Press Space to play/pause, Left/Right to skip 5 seconds, or M to mute. Up/Down and A/D still navigate files.
• Compact controls sit over the video and hide during playback after inactivity. The … menu provides loop, properties, open, and audio information. Image editing bars are hidden while viewing video.
• Use the fullscreen button or Ctrl+F for native fullscreen with the complete frame fitted to the screen. Only the video remains after the controls and cursor hide; moving the pointer or pressing a key reveals the controls. Esc returns to the window (or closes the playback menu first).
• One active player keeps inactive tabs lightweight. Playback position survives tab changes and, when session restore is enabled, restarts.
• Video thumbnails are static frames. Image editing, image copying, wallpaper, and print/export actions are disabled for videos. Slideshows continue to show images and skip videos.
• Unsupported video codecs show an error. Silent videos play without automatic audio notices; volume and mute are dimmed and disabled when playback yields no decodable audio, and recover if audio becomes available later. Audio information is available on request in the playback menu. HEVC and multichannel audio are not universally supported; there is no bundled transcoder or external player dependency.

YouTube videos and playlists

• Choose Open YouTube link in the main menu or press Ctrl+L. Paste a video, Shorts, live stream, or public playlist link. Links containing a video and a playlist retain that context; timestamps and playlist indexes are supported.
• The official YouTube player provides playback, volume, captions, quality, and its playlist selector. CyberViewer adds previous/next, playlist repeat, retry, opening the current video in YouTube, and native fullscreen (Ctrl+F, Esc to exit). Its footer stays outside the video and disappears in fullscreen.
• Autoplay on open in the link dialog shares the saved local-video preference. YouTube can still require a click on its own Play button. One online player is active at a time; changing tabs or suspending the application releases it. Optional session restore retains the current item and playback position.
• Internet access and permission to embed are required. Private, age-restricted, removed, region-blocked, and embedding-disabled items may be unavailable. Errors offer retry or opening in YouTube. This phase uses the embedded playlist directly, without a separate searchable playlist catalog, account sign-in, or downloads.
• YouTube controls its stream, recommendations, advertising, and data processing under its own policies. Remote content runs in a separate sandbox without access to CyberViewer's file or settings APIs.

✏️ Editing

• Rotate: left 90° (Q) or right 90° (E) with save/discard workflow
• Crop: interactive overlay with handles and optional create-copy mode
• Resize: width and height controls with aspect lock, presets (720p, 1080p, 25%, 50%, 200%), and quality resampling
• Adjust: brightness, contrast, saturation, blur, grayscale, and invert with live A/B preview
• Flip: horizontal (H) or vertical (Shift+H)

🎬 Slideshow

• Start, pause, and stop controls with a dedicated HUD
• Configurable interval: 2s, 3s, 5s, or 10s
• Loop mode for the current folder
• Option to enter fullscreen on start

📁 File Operations

• Save (overwrite) or Save As
• Copy the image to the clipboard (Ctrl+C) or copy its file path
• Move to trash (Delete)
• Show in folder or open the containing folder
• Export to PDF and Print with page size, orientation, and margin controls
• Set as wallpaper with Fill, Fit, Center, or Span styles
• Favorites with dedicated add, remove, and view actions
• Recent history with up to 10 files and 10 folders

⚙️ System Integration

• System tray: custom HTML popup menu with recent images, plus minimize/close-to-tray behavior
• Auto-start with Windows: launch minimized on sign-in
• Global hotkey: configurable show/hide shortcut, default Alt+Shift+V
• Explorer context menu: right-click supported images to open them in CyberViewer
• File associations: set CyberViewer as the default viewer for JPG, PNG, GIF, WebP, BMP, TIFF, ICO, or AVIF
• Single resident instance: Explorer opens and additional launches send images to tabs in the existing window
• Auto-update: built-in GitHub Releases updater with silent install
• Settings backup: export or import configuration and favorites as JSON

🎨 Customization

• Accent colors: Cyan, Pink, Green, Orange, Violet, Blue, Red, and Mint
• Background styles: Checker-dark, Checker-light, or Solid
• Interface tweaks: sidebar, toolbar, status bar, tooltips, shortcut guide, auto-hide delays, and double-click behavior
• Tabbed settings: General, Appearance, Interface, Slideshow, System, and Backup & Data

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🚀 Getting Started

Install (Recommended)

1. Download the latest installer or portable build from Releases
2. Run the CyberViewer-Setup installer or the portable executable
3. Launch CyberViewer and press Alt+Shift+V to show or hide it from anywhere. No other requirements needed: you do not need Node.js

🛡️ Windows SmartScreen

Windows may show a SmartScreen warning the first time you run the CyberViewer installer: this is an unsigned hobby app, so Windows hasn't built reputation for the file yet. This is expected; the source is public so you can inspect exactly what it does. The same can appear when launching the portable build.

To continue:

See how to run the installer (step by step)

Windows shows this warning for any installer without a paid code-signing certificate; it does not mean the file is unsafe. Do not click "Don't run":

1. Run the installer. Windows may show the blue "Windows protected your PC" dialog.

2. Click the small More info link.

3. Click Run anyway. The installer starts normally.

You can verify the file independently: compare the SHA with the GitHub release, scan it on VirusTotal, or build from source. More details: SmartScreen guide on the website.

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🛠️ Tech Stack & Architecture

• Platform: Windows 10 / 11 (x64)
• Framework: Electron 35.5.1 + vanilla JavaScript
• Security: contextIsolation: true, nodeIntegration: false, custom cvlocal:// protocol with path allowlist, CSP headers
• UI: Custom frameless window, DWM-rounded corners, multi-monitor DPI-aware

CyberViewer/
├── main.js              Electron main process: IPC, tray, protocol, and window management
├── preload.js           contextBridge → window.electronAPI (secure IPC)
├── tray-preload.js      Tray menu preload
├── CyberViewer.html     Shell markup (all UI modals/menus)
├── tray-menu.html       Custom tray popup
├── css/app.css          Styles
├── js/
│   ├── app.js           Renderer UI logic
│   └── media-helpers.js Pure helpers (mediaUrl, canvasExport, filters)
├── lib/                 Shared Node helpers
│   ├── paths.js         Path normalization, allowlist, MIME types
│   ├── thumb-cache.js   Thumbnail caching/eviction
│   ├── window-bounds.js Window bounds clamping/DPI awareness
│   ├── updater.js       electron-updater integration
│   └── settings-backup.js Import/export settings
├── i18n/
│   ├── menu.json        Menu, tray, and dialog strings (EN/ES)
│   ├── ui.json          Renderer UI strings (source of truth)
│   └── ui.js            Generated loader (npm run i18n:sync)
├── assets/              Icons
└── test/                Node unit tests

Building from Source (Developers)

Only needed if you want to work on CyberViewer or build it yourself; regular users can skip this section.

Prerequisites

• Node.js LTS → https://nodejs.org
• Windows 10/11 (x64)

Development

cd C:\path\to\CyberViewer
npm install
npm start

Checks and localization

npm test
npm run lint
npm run test:workspace # isolated image/tab regression tests
npm run test:video     # isolated video tests; requires FFmpeg on PATH (development only)
npm run test:youtube   # live YouTube/playlist tests with an isolated profile; requires internet
npm run i18n:sync       # regenerate i18n/ui.js from i18n/ui.json

Build (Production)

npm run build            # NSIS installer + portable
npm run build:portable   # portable only

Outputs (in dist/)

Artifact	Description
CyberViewer-Setup-<version>.exe	NSIS installer
CyberViewer-Portable-<version>.exe	Portable build

NSIS Installer Features

• Optional "Set CyberViewer as default image viewer" (checked by default)
• Per-user (HKCU) file associations
• Desktop/Start Menu shortcuts
• Bilingual installer (en_US, es_ES)

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⌨️ Keyboard Shortcuts

Key	Action
Ctrl+O	Open images or videos
Ctrl+L	Open a YouTube video or playlist link
Ctrl+Tab / Ctrl+Shift+Tab	Next / previous tab
Ctrl+W	Close tab
Ctrl+Shift+T	Reopen closed tab
Ctrl+Shift+O	Open containing folder
Ctrl+Shift+F	Open folder
Ctrl+S	Save As
Ctrl+P	Print / Export PDF
Ctrl+C	Copy image to clipboard
Ctrl+V	Paste image from clipboard
Ctrl+D	Toggle favorite
Ctrl+,	Open settings
Ctrl+I	Properties
← → ↑ ↓ / A D	Navigate files; in video, ← → seek 5 seconds
Space	Next image, play/pause video, or play/pause slideshow
M	Mute/unmute video
Q / E	Rotate left / right 90°
C	Crop
R	Resize
J	Adjust (color/tone)
H / Shift+H	Flip horizontal / vertical
F	Fit to window
1	Original size (1:1)
Enter / G	Toggle fullscreen
S	Start/pause slideshow
Delete	Move to trash
+ / -	Zoom in / out
0	Fit to window
Esc	Close overlays/modals/cancel crop

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🔒 Security

• webSecurity enabled with Content-Security-Policy
• Local images served through cvlocal:// protocol (streamed) with path allowlist
• Allowlist expansion only accepts existing supported image or video files
• Folder scans only run for neighbors of an existing supported media file
• Media streams support byte ranges for seeking without reading a complete video into RAM
• Renderer runs with nodeIntegration: false and contextIsolation: true
• DevTools IPC disabled in packaged builds

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🔄 Updates

Installed (NSIS) builds use electron-updater against GitHub Releases:

1. About → Check for Updates (or menu Help)
2. Download update when a newer version is available
3. Install & restart: silent install, no wizard, and automatic relaunch

Download/install is always user-requested. With "Check for updates on startup" enabled (default), the app notifies on startup that an update exists (toast + About banner), but will not download until you ask.

Portable builds cannot self-update in-app; use Open releases page.

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❤️ Donate

After countless hours building and refining CyberViewer for my own use, I recently decided to share it with the world along with my other open-source tools in CyberGems.

If you’d like to support future updates, I’d truly appreciate it. Your donation helps keep development going, roll out new features, speed up updates and bug resolution, and enhance documentation quality. You can also show your support by starring the repo on GitHub. Thank you! 🙏

Crypto donations (BTC, ETH, USDT, LTC): click to view addresses

Asset	Address	QR
BTC	bc1q5mxzz05nmvsheqzx7970euswta3fksxzcfzag4
ETH	0x79b703Ec0f77493679Fcd280aF3b983E20c580B8
USDT (ERC20 / BEP20)	0x79b703Ec0f77493679Fcd280aF3b983E20c580B8
USDT (TRC20)	TSVbSk1HSyZ1NprCnAYiw56ECwXgH887mD
LTC	LWGnEHgcFCE2BRkzLnsdPDD8Y8ZeDK577X

⚠️ Send only the selected asset on the indicated network. Using the wrong network will result in permanent loss of funds.

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📄 License

CyberViewer is distributed under the terms of the GNU General Public License v3.0. See LICENSE for the full license text.

Copyright (C) 2026 CyberGems

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❓ FAQ

For frequently asked questions, troubleshooting guides, and detailed configuration instructions, visit the FAQ or the online documentation.

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Thanks for using CyberViewer! 🎉

Made by CyberGems

         

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🔗 See also

More free, open-source, privacy-first apps from CyberGems:

App	Description
🕐 CyberClock	Desktop clock with analog & digital display, calendar, timer, stopwatch and relaxation module.
📢 CyberFeeds	High-performance, local-first RSS and Atom reader built for speed, privacy and clean reading.
🚀 CyberLauncher	Windows application launcher with hot corners, scheduler, system monitor and integrated terminal.
💻 CyberManager	Lightweight, high-performance task manager, virtualized and NT-native, a powerful Task Manager alternative.
📝 CyberNotes	Privacy-focused note-taking app with rich text, folders, tabs and bcrypt-protected local storage.
⚡ CyberPaste	Privacy-first clipboard manager for text, code, images, HTML and files.
📸 CyberSnap	Screen capture and annotation suite with vector tools, high-speed OCR, screen recording and color picker.
⭐ CyberTray	High-performance tray launcher with hotspots, system monitoring, process manager and PIN-protected file vault.
🛡️ CyberWall	User-friendly Windows firewall with real-time per-app rules powered by the WFP kernel engine.

➡️ Browse all apps at cybergems.org