Cardstock

Cardstock is a calm, offline flashcards app. Make a deck, study it, get on with your day. No account, no sign-up, no subscription, and nothing to dismiss before you can start.

Your cards stay on your device, and your decks are files you own.

FOUR WAYS TO STUDY, ALL INCLUDED
Review: spaced repetition built on FSRS, a modern open scheduling algorithm. It works out roughly when you are about to forget a card and shows it to you then, so short sessions are enough.
Learn: a card has to pass multiple choice and then typed recall before it counts as learned. Typing is marked forgivingly, so one typo or a different accepted wording does not count against you.
Match: a quick timed grid where you pair terms with definitions. Good for the five minutes before a lesson.
Test yourself: an auto-generated quiz mixing multiple choice, true or false and typed answers, scored at the end. Every test is kept, so you can retake it, compare attempts, and read back exactly what you answered.

STUDY BOTH DIRECTIONS
Switch on both directions and a deck asks you term to definition and definition to term, without duplicating a single card. Each direction keeps its own memory, because recognising a word is a different skill from producing it.

CARDS THAT HOLD MORE THAN TWO LINES
- Images on either side
- Labelled extra fields for things like plural, gender or an example sentence
- A note for a mnemonic, shown after you answer and never tested
- Extra accepted answers for typed recall
- A colour per card, useful for grouping things like German noun genders
- Folders inside folders, so one language can hold topics which hold decks

READ ALOUD
Tap the speaker and hear the card in the right voice. Set a language per deck side, or per card, and each part is read in its own: the term in the language you are learning, your own note in your own language. 28 languages, using the speech engine already on your phone. Cardstock can also work out a deck's languages from the cards themselves, on the device, with no network call.

YOUR DECKS ARE FILES
Export a deck as a .deck file to share it, or save it to your phone and keep it. Import one the same way. The format is a plain zip holding readable JSON and it is publicly documented, so a deck you made is still yours even if you stop using this app. Coming from another app? Import an Anki .apkg file or a CSV, or paste a two column list and it becomes cards.

BACKUP YOU DO NOT HAVE TO REMEMBER
Cardstock backs itself up daily and keeps a rolling set, so a bad day costs you nothing. The newest copy is also kept in your Downloads folder, where uninstalling the app cannot reach it. Restore in one step after a reinstall, or switch on Google Drive for an off-device copy in a private folder only Cardstock can see.

OPTIONAL AI, WITH YOUR OWN KEY
Add your own API key for Gemini, OpenAI, DeepSeek or Claude. Gemini has a free tier, so you can try all of this for nothing.
- Draft a whole deck from a description
- Have a test written about what your cards mean, not just what they say
- Let AI mark your typing, so a synonym or a missing article still counts, with a sentence saying why
- Work on a deck you already have: fill in what is missing, check it for mistakes, add more cards
You approve every change before anything is saved. Your key lives in your device's secure storage, the cost is whatever your provider charges you, and there is no Cardstock account or server in between. Leave AI switched off and none of it ever runs.

PROGRESS WITHOUT GUILT
A quiet summary of what you have studied and how your recall is holding up. No streaks to break, no badges, no notifications nagging you.

PRIVATE BY DEFAULT
No account. No analytics. No tracking. Everything you write stays in a database on your device. Things leave your phone only when you ask: sharing a .deck file, switching on AI with your own key, or turning on Google Drive backup. Your AI key is never included in a backup.

English and German throughout. Works fully offline.

Recent changes:
Cardstock 1.1 adds tests that span your decks.

- A new Tests tab, keeping every test you build across decks and what you scored.
- Pick the decks, set an exact share from each, and go.
- Have AI write those questions, when your decks fit in one request.
- Deck notes: reference material you keep beside a deck and never study.
- Any emoji you like on a deck or folder.

Cardstock now shows one small ad, on the screen at the end of a session and nowhere else. You can turn it off for a day.