Save private window data web browser extension

Save cookies, localStorage, IndexedDB, and other website data in private windows and restore them when a new private window is opened.

For preserving website data (settings, to stay logged in to websites, offline app data, etc.) in private windows.

Features

• Cookies - Always saved (core functionality)
• localStorage - Website settings and data
• IndexedDB - Offline web app databases
• Cache API - Offline assets (optional, disabled by default)

How to use

1. Install the extension and enable it in private windows
2. Open a new private window
3. Configure and/or log in to websites in the private window
4. Use the Save Now button or enable Auto-save on changes in the extension popup
5. The private window can be closed now, the saved data will be restored automatically when a new private window is opened

Popup Interface

Click the extension icon to access the popup with:

• Enable/Disable toggle - Turn the extension on or off
• Save Now - Manually save all data from current private windows
• Restore - Manually restore data to current private windows
• Storage type toggles - Choose which types of data to save:
  • Cookies (always on)
  • localStorage
  • IndexedDB
  • Cache API (optional)
• Auto-save on changes - Automatically save when data changes
• Backup/Restore - Export and import saved data as JSON
• Delete - Clear all stored data

Data Reconciliation

When enabling the extension while a private window is already open, you'll be asked how to handle the existing data:

• Save current data first - Save what's in the private window before enabling
• Restore saved data - Overwrite current private window data with saved data
• Skip - Enable without changing any data

Privacy Note

This extension is designed to preserve data across private browsing sessions. This data is stored locally on your device. No data is collected or transmitted.

⚠️ Warning: This extension defeats some privacy protections of private browsing by persisting data that would normally be cleared. Only use if you understand and accept this trade-off.

Permissions

• Access data for all websites: to save and restore cookies and web storage in private windows for all websites
• Download files and read and modify the browser's download history: to backup the saved data
• Clear recent browsing history, cookies, and related data (Mozilla Firefox only): used to clear all cookies in open private windows when using the Delete button and on Restore

Screenshot

Popup Interface

Development

This repository contains two manifest files for different browsers:

File	Browser	Notes
manifest.json	Chrome/Edge	Uses service_worker for background
manifest-firefox.json	Firefox	Uses scripts array for background

Install / Loading Unpacked Extension

Chrome / Edge:

1. Go to chrome://extensions (or edge://extensions)
2. Enable Developer mode (toggle in top right)
3. Click Load unpacked
4. Select the extension folder (containing manifest.json)
5. Go to extension details → enable Allow in Incognito / Allow in InPrivate

Firefox:

1. Rename manifest-firefox.json to manifest.json
2. Go to about:debugging#/runtime/this-firefox
3. Click Load Temporary Add-on
4. Select manifest.json from the extension folder
5. Go to about:addons → extension settings → enable Run in Private Windows

Backup File Format

The backup file is a JSON file with the following structure:

{
  "version": 2,
  "timestamp": "2024-01-01T00:00:00.000Z",
  "cookies": [...],
  "webStorage": {
    "https://example.com": {
      "localStorage": { "key": "value" },
      "indexedDB": [...],
      "cacheStorage": [...]
    }
  }
}

Version 1 backup files (cookies only) are still supported for import.

Credits

• Original from Adam777Z
• Icon from Bootstrap Icons v1.5.0 (box-arrow-in-down)