The best way I found to block websites on my phone is to use DNS66. You can download it from the F-Droid app store (it is not on Google Play). It creates a VPN that will block any website on the blacklist.
Its original goal is blocking ads and trackers. It comes ready with multiple ad and tracker lists. New lists can be added, which is how I am blocking distracting websites.
It is better than similar products on the Google Play Store because:
- It is open source, free, and has no ads.
- It does not proxy web traffic. Blocking is all local.
- It does not require root.
- It is not going to try to steal your data.
To use it, you will create a text file and redirect websites you don’t want to 127.0.0.1. Or you could be funny and redirect to a good websites like wikipedia.org. I prefer to host my file online (like dropbox.com) and download it. Below is the file format.
127.0.0.1 instagram.com
127.0.0.1 www.instagram.com
Man and Keyboard 