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How to Block Bad Websites—or Just Get Things Done
The web is full of distractions and temptations, especially when we really should be working. Here are some tools to help you stay focused.
i have used BlockSite before
BlockSite is a free browser extension for Chrome and Firefox, and an app for Android and iOS, that does exactly what it says it will: block websites for you
https://www.wired.com/story/how-to-block-websites-chrome-firefox-ios-android/