Focused

Focused is an open-source, lightweight extension that helps you to improve focus and increase productivity by blocking distracting websites.

It's super simple to use. Just add distracting website domains to the blocked list once, and the extension will prevent you from visiting them. After work, you can turn off the focus mode and surf the internet without limitation.

A list of the blocked websites is being saved only in your Browser storage. Therefore only you have access to it.

Moreover, the software is an open-source project, meaning its source code is open to everyone, which is an assurance that your data is accessible only within your browser.

Source code of the project: https://github.com/dimimikadze/focused