There are browser extensions like Leechblock for Firefox, they help. You can make the list of sites to edit impossible to reach during the time they are blocked

There are browser extensions like Leechblock for Firefox, they help. You can make the list of sites to edit impossible to reach during the time they are blocked. I'd like a tool like that but more low level, so they work for all browsers simultaneously and can be even harder to circumvent. There's also a browser extension that limits the number of tabs you can have open. Maybe another good one would be to slow you down, e.g. at most one page per minute or so. But the best remedy is to stand up and walk around for a bit, discuss what's vague about your current task with a colleague for a moment, or try to put some thoughts on actual paper. That's not something you get from a product.