I just don't use an app. I will challenge myself to remember things or practice things manually.
It's probably sub optimal compared to structured spaced repetition, but it works well enough for me.
Every time i did repetition, i've made a shorter note about the subject.
Then next repetition cycle, i'm reading the note, and making shorter note based on it. and so on.
once few cycles i'm re-reading the main starting note i made.
I tried it for a while with my eldest child (then aged 3) to help her remember numbers, letters, etc. She didn't find it very fun past the first couple of times, so I figured I wasn't going to hoist it on her.
• Memorizing Geoguessr metas. Made it to Master I rank this way.
• Memorizing new words. When I come across a word I don't know, I make a new flashcard for it.
• Memorizing things about people. My wife's favorite ice cream flavors, which spices each of my children dislikes, etc.
Anything I want to memorize but wouldn't be exposed to frequently enough in my day to day life. Flashcard review takes only a few minutes each day.
I downloaded an existing deck and modified it so that only the correct answer is shown instead of multiple choices.
I still can remember some of the content even though I deleted the deck short after receiving my license.
I got introduced to this idea a few years ago from AJATT [1] and my personal experience is that it works very well.
[1] https://web.archive.org/web/20100406173634/http://www.alljap...