The best spaced repetition apps
The best spaced repetition app depends on how much control you want over scheduling. Anki gives the most, for free. Recall applies FSRS for you with almost no settings, and RemNote builds reviews into your notes.
In short
- Anki offers FSRS with an optimizer and fine control, but its settings take time to learn.
- Recall is the easiest way to use FSRS: it is set up for you.
- RemNote suits people who want reviews inside their notes, and Mochi people who want quick two-button reviews.
- SuperMemo for Windows has the most advanced algorithms, for learners willing to master a complex tool.
How do the best spaced repetition apps compare?
All five apps schedule each card on its own, but they differ in the algorithm they use, how you grade a review and how much you can adjust.
| App | Best for | Algorithm | Grading | Price | Platforms |
|---|---|---|---|---|---|
| Anki | full control over scheduling | FSRS or SM-2 | 4 buttons | Free; iOS app US$24.99 | Web, iOS, Android, Mac, Windows, Linux |
| Recall | ease of use, with FSRS set up for you | FSRS | 4 buttons | Free plan; Pro US$11.99 a month or US$59.99 a year | Web, Claude, ChatGPT |
| RemNote | spaced repetition inside your notes | SM-2, or FSRS (beta) | 4 buttons | Free plan; Pro US$10 a month or US$96 a year | Web, iOS, Android, Mac, Windows, Linux |
| Mochi | quick two-button reviews | Its own, or FSRS | 2 buttons | Free; Pro US$6 a month or US$60 a year | Web, iOS, Android, Mac, Windows, Linux |
| SuperMemo | the most advanced algorithms | SM-20 and four others | 6 grades | Windows US$64 one-time; app free tier, Premium from US$99.99 a year | Windows, Web, iOS, Android |
Anki
Best for full control over scheduling
Anki is the best-known spaced repetition app. It offers FSRS, with an optimizer that fits it to your review history, and the older SM-2 scheduler. Almost every step of scheduling can be adjusted, which rewards learners who take time to understand the settings.
Strengths
- FSRS with an optimizer, and SM-2
- Free and open source
- Huge library of shared decks and add-ons
Limits
- Many settings, with little guidance on which matter
- iPhone and iPad app costs US$24.99
Recall
Best for ease of use, with FSRS set up for you
Recall is a web app built on FSRS that keeps settings to a minimum: a daily number of new cards and a target retention. Making and editing cards is simple, and AI can fill them in. It imports Anki decks with their review history.
Strengths
- FSRS without any tuning
- Simple card editing, with AI to fill in cards
- Imports Anki decks with their review history
Limits
- Runs only in a browser, with no offline mode
- Fewer settings and statistics than Anki
RemNote
Best for spaced repetition inside your notes
RemNote turns lines of your notes into flashcards and reviews them with spaced repetition. It uses SM-2 by default, and offers FSRS as a beta option. An Exam Scheduler can plan your reviews around an exam date.
Strengths
- Notes and flashcards in one place
- Exam Scheduler for a fixed date
- Unlimited cards on the free plan
Limits
- FSRS still in beta
- Many features and settings to learn
Mochi
Best for quick two-button reviews
Mochi grades each review with just two buttons, Remembered or Forgot. Its own algorithm moves intervals up or down by fixed steps, and FSRS is an option with a target retention you choose. Cards are written in Markdown.
Strengths
- Fast reviews with two buttons
- Free with unlimited cards, offline on every platform
- FSRS available
Limits
- FSRS has no built-in optimizer
- Sync between devices needs Pro
SuperMemo
Best for the most advanced algorithms
SuperMemo for Windows runs five algorithms side by side, including SM-20 and FSRS. Each gets more weight in your schedule the better it predicts your recall. It also offers incremental reading, but its interface takes time to learn.
Strengths
- The most advanced scheduling of any app here
- Incremental reading
- One-time purchase
Limits
- Runs only on Windows
- Complex interface
What matters in a spaced repetition app?
The scheduling algorithm matters most, then how easy the app makes it to keep reviewing every day.
- The algorithm. FSRS estimates how likely you are to recall each card and schedules a review when that falls to a target, such as 90%. SM-2 multiplies each interval by an ease factor. Its developers report fewer reviews than SM-2 for the same retention, based on simulations.
- Grading. Four buttons give the algorithm more information; two buttons make reviews faster.
- Settings. More settings allow fine tuning, but also more ways to get something wrong.
- Where you review. Daily reviews are easier on the devices you carry, so check the platforms and offline use.
How did we choose these apps?
We selected five apps built around spaced repetition, each suiting a different kind of learner. Every fact comes from our app profiles, which are checked against each app’s official website, documentation and store listings.
Which other apps did we consider?
Quizlet offers spaced repetition only as an option in Flashcards on its website. Knowt has a free spaced repetition mode, but does not document its algorithm. Both are built mainly for revision before a test, so we left them out of this selection.
Frequently asked questions
What is the best free spaced repetition app?
Anki is free with no limits on Windows, Mac, Linux, Android and the web, and offers FSRS. Mochi is also free with unlimited cards, on every platform. Recall and RemNote have free plans with some limits.
Which spaced repetition apps use FSRS?
Anki, Recall, Mochi and SuperMemo for Windows all offer FSRS. Recall uses it by default; in Anki and Mochi you switch it on. RemNote offers it as a beta option.
Is Quizlet a spaced repetition app?
Not mainly. Since August 2026, Quizlet’s website offers an optional spaced repetition method in Flashcards, but its other study modes only quiz you within a session.