But this article is about 3 different "front ends" if you will, that enable searching the Chronicling America site very differently. I will describe them below, and they are not presented in any preferred order. All are very different.
Elephind

The key for this discussion though is that Chronicling America is one of the collections. The search capability is good, and doesn't have all of the bells and whistles that other sites do - but it is fast and accurate (and you can combine a CA search with state based collections.)
It is cool that one can not only search Chronicling America but multiple sites from the U.S., all at the same time.
Old News USA
FYI, Revgenea won the RootsTech 2017 Innovator Showdown earlier this year in Salt Lake City. Personally, I have used this app quite a bit, and it has a wide variety of features.
It is cool that one can search Chronicling America from a mobile device. Makes for being productive while waiting 15 minutes for an appointment.
US News Map
It is cool because of the display features of the search results. Seeing visually where in the U.S. the Chronicling America search results are located is terrific. (Hat tip to Lisa Louise Cook for making me aware of this. Check out her SIte for a video of this software).