Does it says it will do. Fast and efficient.
You an't create custom folders as far as I can tell, only rename the groups already created by OneTab.
It's amazing. 99% of the time I never go back to the tabs I save, but that's the beauty of it. I think most of the people who suffer form having tens of tabs open suffer from the version of FOMO. OneTab is a perfect solution for that - you tell yourself you won't miss out or lose the website you want to read "later", because it's safely saved, but you actually don't have to go back to it and waste time on it, while your brain is perfectly happy and calm knowing, that if you need to go back to it, you can.