What is Spoofing and why is it needed?

From time to time a website will decide to block Vivaldi users from accessing their pages. They can do this by looking at our “User Agent”. The User Agent is a piece of information that is sent from the browser to the website when it connects, telling the site which browser is being used.

Sometimes the development team of a website will naïvely assume that only tested browsers should be given access to their site. They use the User Agent information, to block browsers that they consider to be unsupported. Since Vivaldi is based on current web standards and uses an up to date copy of Chromium/Blink (one of the most popular rendering engines), there is usually no good reason to block us. The following is a quick guide as to how to work around such website blocks, should you encounter them.

Spoofing your User Agent

It is possible to spoof (fake) the User Agent directly in Vivaldi, however this currently requires the use of a command line switch and the new User Agent would be sent to every website you view. Being able to make the change ‘site-specific’ ensures that other websites continue to recognise Vivaldi users and thus see the growth of our user base, which helps to ensure less of these issues in the future. Therefore it is better to use a browser extension to handle this and then limit its impact to the problematic website(s).

There are many User Agent spoofing Extensions. Most of them have preconfigured User Agents for very old browsers and are intended for web developer usage. We therefore suggest “User-Agent Switcher and Manager” because of its comprehensive and up to date list, of pre-configured user agents.

After installing “User-Agent Switcher and Manager” click on its icon and select a new User Agent. It is recommended that you pick a recent Chrome user agent for best compatibility. Then click “Apply”.

Site Specific Spoofing

To limit the effect of this extension to specific websites, click on “Options” from the extension drop down and add the domain names you wish to block to the “White-list” (remembering to click “Save” at the bottom of the Window when you are finished).


Some websites that make use of Cookies or Web storage may continue to have issues, if this locally stored data references either the User Agent (before spoofing) or past connection failures. If you suspect this, open ‘Developer Tools’, click on the ‘Application’ tab and use the ‘Clear Storage’ options to clear all the site data (remember to check the box for ‘Cookies’ as well).

Reporting websites

If you do encounter issues with websites blocking Vivaldi (or behaving differently) based on User Agent we recommend you politely report the issue to the website in question. Often they will remove their block and allow Vivaldi users to access the page in question, once they are made aware.

You may also wish to report an issue to us. This allows us to reach out to them as well, and in cases where websites are non responsive to requests for removal of the blocking, we may build in a workaround for that website directly.


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