Awesome. Just Awesome.
To get Awesome indeed rating from me, which is even more awesome than Just Awesome, consider this;

-Pinned tab should have an option to ignore them
-Include some kind of obvious visual alert, when new tabs aren't allowed to be open anyomore. For all of us having sound turned off. :D

Much appreciated, Mr. Rudolf!

The sound for trying open a tab in excess is strange at first, but it keeps kinda funny while being a real alert! And the main limit is just flawless! Thanks! Hope everything goes well for you and your son! :)

I just would like another mechanism for limiting tabs, prevent opening new ones rather than closing older ones... exept that it's nice.

I love it. It would be nice for there to be an option to add a button to the address bar that would allow you to change the number of tabs allowed or toggle it on and off more easily.

A life-saver for me. I happily avoid too much procrastination because of this.

Jesus would approve this add-on

Great! Anyway to change limit?

Awesome!