There are plenty of bird identification app or books or websites, is there anything similar for dinosaur tracks?
I get that identifying dinosaur tracks is hard, if I remember correctly there are only three known sets of T-Rex tracks in the world, and it looks like many tracks are unidentified.
Still it would be cool if there were resources for this.
There are resources, but be aware that it is rather difficult to get a definitive answer.
Here is a digital book published by the Earth Sciences department of the University of Bristol with a section on identifying track makers: http://palaeo.gly.bris.ac.uk/Palaeofiles/Tracks/default.html
Here's a page at the UC Berkeley Museum of Paleontology, and notice specifically the section near the bottom on identifying tracks: http://www.ucmp.berkeley.edu/science/trackways/trackways4.php
Here's a page on the Smithsonian site about identifying dinosaur fossils, with a section dedicated to tracks: https://naturalhistory.si.edu/exhibits/backyard-dinosaurs/faq.cfm
In all of these, you'll notice a trend that identification can be extremely difficult. The reason for this is because we are having to extrapolate from a skeleton what a complete foot would have looked like, in addition to the fact that dinosaur tracks are rarely perfect molds. However, there is ongoing research into modeling the tracks of extant species with respect to their skeletons, and a lot of headway has been made using this technique.
Are there resources for identifying dinosaur tracks?
No;
Dinosaur tracks are called trace fossils
Trace fossils are classified in various ways for different purposes. Traces can be classified taxonomically (by morphology), ethologically (by behavior), and toponomically, that is, according to their relationship to the surrounding sedimentary layers. Except in the rare cases where the original maker of a trace fossil can be identified with confidence, phylogenetic classification of trace fossils is an unreasonable proposition. Source
The two Wikipedia articles linked above, make for interesting reading, but the short answer to your question is, no there is no resource categorizing them, as in most cases there is no evidence indicating what animal actually left the prints.
The study of dinosaur tracks is included in Paleoichnology which covers all the trace fossil types. It would seem the best reference would be an Ichnology text book, I googled around and did not find anything was freely available and looked like it would work as a reference.
There are a few dinosaur tracks that are identifiable. There are even some parks like Dinosaur Valley State Park where a few types of tracks can be viewed, with very clear references for a very limited number of species. I do not believe these qualify as "resource" as the OP seems be looking for more of a field guide for identifying tracks (Trace Fossils) found in non-developed areas.
