I use 2 different apps since neither offers differentiation between flocks.
Mother Hen is a cheap one time payment app that I use for my breeding flock and Flockstar is a free app I used to track my egg production flock.
Both offer expense tracking and photo identification per bird. They also allow you to track how many eggs you get each day with the option to put an egg for a specific bird
What are you keeping track of? You might find an App to be more trouble than a good old pen and paper. I guess to each their own- but usually long-term chickeners do best with a simple set schedule. It becomes part of your day and life.
Don't have any advice on apps, but I just use a board or note book to keep track of things, less likely to have issues. most back yard flocks don't need it, might be a bit harder if you have a flock of 200+ though