This app was mentioned in 1 comment, with an average of 1.00 upvote
Computer: https://chrome.google.com/webstore/detail/nanny-for-google-chrome-t/cljcgchbnolheggdgaeclffeagnnmhno
Android: https://play.google.com/store/apps/details?id=com.contentwatch.ghoti.cp.browser&hl=en (you'll have to set reddit to be blocked)