What is "Spoof Timezone" extension and how does it work?

The purpose of this extension is to prevent websites from identifying your possible location by using the Intl.DateTimeFormat().resolvedOptions() or new Date() JavaScript methods. It achieves this by adding a wrapper to both methods that change the browser's timezone to the one defined by the user on the options page. The extension configures your timezone to "Europe/London" (GMT +0000) by default after installation. You can change it from the options page. Also, you can easily turn the timezone spoofing feature on or off by clicking the toolbar button (this feature is not available anymore on the manifest v3 port). To check your current timezone, you can use the tool located in the right-click context menu over the action button.

This is what websites can gather using these methods:

You can refresh this page after the timezone is modified to see if the extension is working as expected or not. To see all countries at different UTC time offsets take a look at wikipedia.org/.../List_of_UTC_time_offsets page

Based on your browser WebExtension implementation the "inline" method might leak your actual timezone!

How can I use this extension to prevent fingerprinting?

In case a fingerprinting algorithm uses your current timezone to create a unique identifier for your browser, you can activate the random timezone feature on the options page. This feature generates a new timezone for you every time a page is refreshed, making it difficult for websites to use your timezone as a way of identifying your browser. It is important to note that with the random timezone setting enabled, the GEO location obtained from your IP address (or proxy software) will not match the timezone offset returned by the JavaScript methods.

What's new in this version?

Please check the Logs section.

Can you provide a way to find the timezone value when using a proxy server to connect to the internet?

You can use the built-in tool. Right-click on the action button and press the update my timezone item. The extension uses an online service to detect your current timezone that matches your IP address and updates the internal value.

Alternatively, you can navigate to https://ipleak.net/ and wait for it to collect all relevant information. Once the process is complete, go to the "Time Zone" section and look for the timezone value corresponding to your current IP address. Use this value on the options page to ensure your browser timezone matches the IP address.

Is it possible for the extension to automatically detect my timezone based on the proxy server I'm using?

Yes, starting from version 0.1.4, the extension includes a new feature in the right-click context menu that automatically detects your timezone. You can also configure the extension to update your timezone every time the browser is restarted. If your timezone has changed since the last update, the extension will send a desktop notification to notify you of the update. Note that this option is not enabled by default.