Blockers. If you want to block some sites on your Windows computer, ColdTurkey isn't a bad choice. Don't bother paying for it and just get the free version (based on my anecdotal experience).
On my Android phone I've gone for BlockSite. I'm reasonably happy with it overall. This isn't a "proper" review in a sense for various reasons. I currently have it set up with a password lock. I'm not sure if this is completely reliable. I did this before and it's possible that sooner or later it just stopped looking for a password. Or maybe I unlocked it deliberately (my method is to write the unmemorable password on a bit of paper and hide it somewhere awkward). It's better than nothing anyway (I think, I'm honestly not sure yet lol), and I'm paying money for it, but it was pretty cheap at the sale price (if you're buying it, quickly agree to any good looking sale offer, or you might have to contact them to get the offer again etc.)
Life's been throwing a lot at me lately, well life and my "issues", but anyway, I'm doing pretty well at responding to a lot of it, I hope! Of course, working on one thing can lead to neglecting something else, but I'm trying to avoid that side effect.