I use Ankidroid and make my own cards. It works on all platforms and is free. Usually just language syntax, and keywords. But there are great free flash cards

I use Ankidroid and make my own cards. It works on all platforms and is free. Usually just language syntax, and keywords. But there are great free flash cards like this one on Kotlin: https://ankiweb.net/shared/info/1229687199 https://ankiweb.net/shared/info/1229687199 I got inspired by Derek Banas video: https://youtu.be/5urUZUWoTLo https://youtu.be/5urUZUWoTLo