Download an app called Evernote. You can take photos of your recipe cards and the app will actually search handwriting to find what you're looking for, as long as the writing is reasonably legible of course. You can place them into categories as well. There are lots of you tube videos giving hints how best to organize with the program. I digitized all of my dear mother's recipes after she passed away a few years ago. Takes about a minute per card/paper, if that, to load each one and put it in it's designated notebook.
Evernote is free if you upload under a designated amount of space each month so if you have a lot of recipes, you might have to do a few hundered and then wait until the next month to add more. Or you can pay for increased storage. Another great thing is that the notebooks are stored on the Evernote servers so you can access them away from home - to pass them along to friends, check while at the grocery store to make sure you have the ingredients, etc.
Besides recipes, I use Evernote to store almost everything - manuals and specs for my yard equipment (lawn mower, trimmer, etc) - how much/type of oil, what plug, when purchased, etc. Another notebook has receipts for anything major I buy - we all know how they have a habit of the ink disappearing!