K2 vs Anki
The Anki alternative with no review pile.
Anki schedules every card for a date, so a week off turns into a backlog. K2 keeps no dates at all: it decides what to show you right now, from how you are answering. See how the two compare, and which one fits the way you study.
No account needed · No due dates · Runs in your browser
K2 and Anki, side by side.
Both are spaced repetition. They disagree about whether a card needs a date.
| Topic | Anki | K2 |
|---|---|---|
| How the next card is chosen | Each card is scheduled for a future review date. By default the interval comes from an algorithm in the SuperMemo SM-2 family; FSRS is an opt-in alternative. | Nothing is scheduled. Each time, K2 picks a random item and rolls the dice: it shows the item only if the roll beats that item’s chance of coming up, p. Items you miss come up often; items you know rarely do. |
| What each item remembers | An interval, a due date, an ease or difficulty value, and a position in its learning steps. | Just one thing: its chance of coming up, p, kept separately for meaning, reading, writing and listening. Every new item starts at p = 0.5. |
| After you answer | You grade yourself with Again, Hard, Good or Easy, and the card gets its next due date. | Get it right and it becomes half as likely to come up; miss it and it becomes twice as likely. After 3 right answers in a row it is down to p = 0.0625, so when it is drawn it is passed over 94% of the time. |
| After a week off | Reviews keep falling due while you are away and wait for you as a backlog. | Nothing falls due, so there is no backlog. Your next session picks up exactly where you left off. |
| Adding new material | You decide, with a New Cards/Day limit in the deck options. | Automatic. Once you mostly know the items you are learning (average p < 0.15), K2 adds 5–10 new ones on its own. |
| What you study | Anything. You write your own cards or download shared decks, with audio, images, video and scientific markup. | Curated decks: 1,006 kanji (school grades 1–6) and their compound words, plus Chinese, Korean, Spanish, French, Latin and more. Your own cards through Bring Your Own Data. |
| Settings | Extensive: deck options, card templates, and add-ons that extend the app. | Deliberately none for the scheduler. There are no intervals or limits to tune. |
| Where it runs | Desktop apps for Windows, macOS and Linux, AnkiWeb, AnkiMobile on iOS and AnkiDroid on Android. | In any modern browser, with nothing to install. Signing in is optional and syncs progress across devices. |
| Cost | See Anki’s site for each app. | Free, with no account needed. |
Three differences you feel in the first week.
The rest follows from one choice: Anki schedules, K2 selects. The K2 algorithm page explains the method in full.
Selection, not scheduling
Anki gives every card a due date, and studying means clearing what is due today. K2 picks a random item and keeps it only if a random roll beats its chance of coming up, p. Items you miss heat up and come back often; items you know cool and rarely appear, but never leave.
show if roll < pA week off costs nothing
In Anki, reviews keep falling due while you are away, and its manual advises you to stop adding new cards until you catch up. K2 has no dates, so nothing can be overdue: your next session draws from the same probabilities you left.
no due dates → no backlogThe pool grows itself
In Anki you set how many new cards to see each day. K2 watches the items you are still learning, and once they have mostly cooled (average p < 0.15) it adds 5–10 new ones. Struggle, and nothing new arrives until you have steadied.
avg p < 0.15 → +5–10 newWhich one fits you.
An honest answer depends on what you are studying, and how.
Choose Anki if…
- You want to write your own cards, with your own templates, cloze deletions, images or audio.
- Your subject isn’t one K2 covers, or a shared deck for it already exists.
- You want control: tuning intervals, daily limits, or Anki’s optional FSRS scheduler.
- You rely on add-ons, or want native desktop and mobile apps.
- You are keeping a large, mature collection over years, where long review intervals matter.
Choose K2 if…
- You want to start learning kanji today without building or choosing a deck.
- Your study time is irregular, and a backlog of overdue reviews is what made you stop before.
- You would rather not decide how many new cards to add, or when.
- You like short sessions in a browser, with nothing to install and no account.
The two aren’t exclusive. K2 is built for the first pass through a large set, keeping you on whatever you don’t yet know; Anki is built for keeping a collection you have already learned, card by card, over years. Nothing stops you using each for what it does best.
Sources
Claims about other products were checked against their own public pages in October 2026. Features change; follow the links for the current picture.
Start with 日. The engine takes it from there.
Start with kanji — freeHave your own cards in a spreadsheet? Bring Your Own Data studies a CSV or TSV of fronts and backs with the same engine.