I built a free app to track which animals I've seen in zoos and explore zoo inventories.
You can see which animal you can see in what zoo.
And for each zoo you can see their (vertebrate) animal inventory.
You can log which animal you saw and collect lifer lists.
I have just promoted the android app from closed testing to production and I am working on the iOS app.
It has been available as a web app for a few months now.