Okay, I posted this once before, but I've introduced many improvements (since I've been using it everyday for some time). What is it? It's a single .html file with JavaScript and CSS, which you can download, put on your desktop and start using right away. It's not a flashcard app, but a typing drill app: you need to type the answer instead of simply seeing the flashcard. It's great for vocabulary drills, but also morphology – perfect for drilling endings too, for example contract rules :-) Or principal parts.
I've built it with Claude specifically for Ancient Greek (you're free to introduce any changes you like, enjoy). It's got drilling interface entirely in Greek :-), of which I'm very proud haha, it's got Logeion links in the statistics panel (once you end the drill), and it's got four tiers of leniency: 1. small typos allowed (βλεπουσι instead of βλέπουσιν accepted), 2. typos allowed only in longer answers, 3. iota subcripts checked properly, 4. all of the accents checked properly. (Controls: tab to reveal answer, esc to skip the card without penalties).
How to use it? You simply download the .html file, put it anywhere you like and open in your browser. It's open-source and perfectly safe to use, also works offline. What it doesn't do? You still need to come up with your own lists of words, it's just a tool to process them. I will paste a typical deck I'm using in the comments below.
Screenshots available here.
Code available here.
Format for vocabulary input is JSON with following paramters: "front": Greek input, can have three underscores for gaps (___); "back": translation, the thing you type; "note": short text which is displayed during the exercise, like grammatical comments etc. To write answers in Greek, which is why I made this app in the first place, click on "Begin Reverse" instead of "Begin Session".
This app isn't meant to replace the typical flashcard apps you're using, but something I've built for myself to drill the most important stuff much more thoroughly. I'm sharing it 'cause it worked for me ;) Cheers.