Flashcards where you can click on it and it can just be flipped for a quick review while on a hurry? I personally use flashcards that only need to be clicked to reveal the answer while physically writing the answer for kanji. I also need it to have furigana above the kanji because hat way I not only know what the kanji looks like, I also know how to read it in japanese. Probably make audio available too if possible… as soon as i flip the flashcard it either automatically (or not automatically) reads the text for me
Anki can do what you describe.
duolingo tinycards