The folks over at Topsy have also confirmed this bit of news via a tweet as you can see below.
We've searched our last tweet.
— Topsy (@Topsy) December 16, 2015
If you were to go to the Topsy website, it would now redirect users to Apple’s mobile search support page. When Topsy was still operational, it went about analyzing Twitter while providing insights on tweets, users, and events, and such information was repackaged and resold to customers. As to what the future holds for the people over at Topsy? We don’t really know, but keep our fingers crossed that some glad tidings would head their way.