People with money overwhelmingly buy iPhones. $25 is a pittance for anyone who can afford an iPhone. Anybody who uses Anki seriously gets far, far more value than $25 out of it. I used it for well over 200 hours before I stopped and I know I’ll go back to it again.
The Android version is not maintained by the developer of Anki. The iPhone app is. He chooses to charge for the iPhone app, which enables him to make a living making tens of thousands of people’s lives better.
If you don’t want to spend the price of two pizzas on an app that the modal user will use for over a hundred hours don’t.
I used Anki's web interface from my phone for about 6 months before I bought the iOS app. Then about 4 years after using the app almost every day, I sent them another $25 donation. I got way more than $50 worth of value out of it over the 10 years that I used it.
(I've now written my own study tool for Chinese which fixes some of the issues with using flashcards for language learning. Maybe at some point it will show up on "Show HackerNews"; but it's slow going when you've only got a few hours a week.)
* Basic information about countries e.g. population
* Ingredients and dishes from restaurant menus I didn't know
* Important people and places
* History facts (typically from Kindle highlights)
* Conversions between units (e.g. lbs to kg)
* Season for various vegetables and fruits
* Keyboard shortcuts for vim, readline, etc.
* Learning words and terms I don't know from Kindle/Instapaper highlights
* Useful statistics
I bought the iOS app, was happy to do so, and got a lot more than $25 of value from it. In my opinion, the developer might be better off with a subscription model rather than a one-time purchase.
1. Memorizing Japanese vocabulary, pitch-accent, and basic grammar rules. It would probably be useful, at least to some degree, for any language like this.
2. Any certification which required strict memorization. All the basic ComptTIA certs were like this, and the CCNA:R&S cert (unfortunately) required memorizing commands and their syntax.
3. Verses in the Bible (though this is pretty basic in comparison, just Address <-> Text).
In all honestly I think one of the best things you can do if you need to memorize something is make the flash cards yourself, whether with Anki, another app, or even just index cards. This forces you to think about what it is that you're trying to memorize and phrase the text of the cards in a way that you understand. After that, reviewing is just kind of "maintenance" in my opinion. There was definitely a marked difference in my retention when I was using pre-made Anki decks vs. creating them myself. It is also easier to create cards using the desktop app.
It's a side note, but I also don't agree with Anki's pricing model. The app is free on Android[1] but $25 on iOS[2]. I think I heard (I don't have a source) that the developer's justification was that they needed to make money from the all the time and effort they spent creating Anki, plus hosting costs, etc - so why not do a cheaper price on both Android/iOS, or do a free-to-download app with a subscription model? For what it's worth you can use the web version on iOS but the app is a better experience IMO.
[1] https://play.google.com/store/apps/details?id=com.ichi2.anki
[2] https://apps.apple.com/us/app/ankimobile-flashcards/id373493...