It's pretty easy to make your own cage cards. Write or type them out and print them 4-6 on a page on cardstock, from a home printer or at a copy shop; you can get fancy and laminate them so you can use dry-erase pens if you don't want permanent records. An advantage to this approach is that you can customize the cards with the info you want. I have always found that pre-printed cage cards either have spaces I don't use, or don't have spaces for things I want to record. Card-holders you can affix to the cages are spendy so I use clips to hold the cards, like this:
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These clip to the wire and hold the tag out away from the cage so the rabbits can't chew on them. I use them to keep temporary info about who's in the cage.
Alternatively, I use a piece of wide paper tape on the feeder and write the info with a Sharpie.
For permanent records, I use a similar approach to
@Beth42 - I have a wall calendar in the barn where I record breedings (buck and doe), kindlings (who and how many) and mileposts (e.g. "Stardust's bunnies 8 wks").
I do use an electronic record-keeping program as well, but I can't urge you enough to keep records on paper, for the inevitable day when you can't access electronic ones for one reason or another. I keep the old calendars in my files, along with paper copies of all pedigrees, Grand Champion legs, and show reports. Over time this has prevented much heartache.
For electronic records I use Evans Software Rabbit Registry Deluxe version. I absolutely love this program, the fact that it's really user-friendly, and that the technical help has been fabulous (I work well with living things, computers not so much). I've been using it since 2011, so that comes out to pretty cheap in the long run. I also like that it's mine and on my hard drive, so I can use it offline, and my personal information and records are not floating around the ethosphere.
The bad news is that I just heard that Mr. Evans is retiring so at some point in the near future, there won't be any more updates. But the good news is that I will still be able to keep using this program until I or my computer screws it up.
(That's another reason to keep copies of all important data as hard copy!) I'm an old dog and don't like to learn new computer tricks, but if I was just starting, I'd probably look around for another program... although they'll all reach this point at some future date.