iOS
Wox
A box for words.
A box you put new words in and empty a little every day. Build your own deck, or download a free pack in the language you are learning, and let the numbers say which words are actually sticking.
Screens
The parts that matter.
Your words, or a pack you download
The vocabulary you met and want to keep, and a free store of ready-made decks by language when starting from a blank box is the reason nobody starts.
Short enough to do daily
A session that fits in a queue or a lift, because the one that fits is the one that happens.
The numbers say whether it worked
Cards reviewed, sessions run, accuracy overall, and the words sitting below seventy per cent gathered into their own practice. Repetition goes where it is failing rather than where it is comfortable.
A streak you would rather not break
The only mechanic here, and the one that does the work.
No account, no server
Your words stay between your own devices. There is nothing to sign up for and nothing of yours on anyone's machine.
Legal
Every application keeps its own privacy route, one click away.