Umbreon

Open Source Chrome Dark Mode Extension - Make any website dark mode

Creator: Nathan Kasco

Features

• Popup toggle to enable/disable dark mode on the current tab
• Disable Umbreon on the current site or on the current page
• Nightlight setting to attempt enabling Umbreon on any website (requires optional permission)
• Auto-activate list for URLs/origins to turn on automatically (requires optional permission)
• Multiple themes (Classic, AMOLED, Dim, Sepia)

Load Unpacked (Chrome)

1. Open chrome://extensions
2. Enable Developer mode
3. Click Load unpacked
4. Select this project folder (the one containing manifest.json)

Permissions model

• Umbreon starts with minimal permissions (activeTab, scripting, storage) so it can work when you click the extension.
• Enabling Nightlight (or adding to Auto-Activate) will request optional permission to run on all sites (<all_urls>). If you deny it, Nightlight/Auto-Activate won’t run automatically.

Project layout

• manifest.json: MV3 manifest
• src/background/service_worker.js: rule engine + injection
• src/content/content.js: page theming engine
• src/popup/*: popup UI
• src/options/*: settings UI
• src/shared/*: storage, URL helpers, messaging