My farrier told me about one but I can't for the life of me remember what it is... you have to buy it though, but she says it's worth it. You can include all the farrier, worming, vet schedules for all your horses and it will send notifications when they're due for something, you can have all their info, show info, etc. she has ALL of her clients in the app and it sends her a notification when each client is due
I haven't called the farrier in months, she always calls me first to book an appointment. I'll have to ask her what it is next time she's out.