Very good. There are some other time limiters, but as far as I know they limit to a certain amount per day. I want to stop my kids (and perhaps me) from using certain sites (YouTube) for a long time at once. Dawdle Block allows users to set up "blocks" (unintentional pun?) of time in which the time limits take effect so I have created a block for each hour that my child is awake and limit Youtube use to 30 minutes during each hour of the day. That way, at least half the day will be spent on other activities and my child will not watch Youtube for hours at a sitting. Settings can be shared between computers by a export import functionality. The only issue I have is that block settings can only be changed while they are active.

Everything I was looking for in a distracting website blocker!

This is a clean and straightforward addon with all the features needed to make it useful.
Edit: the bug below was fixed
However there is a bug which sometimes causes the timer to not reset at the stated time, and can only then be reset by deleting and remaking the block sets, or waiting and unknown amount of times.

This app works perfectly as advertised. I really like the interface. However, I can't delete Block set 0. I also can't delete URLs from its black list. I tried deleting the extension and then reinstalling it, but the set persisted. I would like the option to delete or edit Block set 0.

EDIT: Thank you very much for the clarification! I believe that is a great way to go about it. In that case, my only request would be to augment the "(some inputs restricted)" note so that it more clearly expresses the reasoning for the restriction. One option is be, "(Blockset timed out. Some inputs restricted)".

EDIT 2: 5 stars because this is a high quality product that works exactly as described and has amazing support by the developer.

very simple add-on to limit your usage on any site.

Does what it says, does it well. No bloated features. Simple. To the point.

Does not time a tab if its not active.
Works in full screen.