fsrs

library6.3.1pypypi✓ verified 81d ago

Python implementation of the Free Spaced Repetition Scheduler (FSRS) algorithm, currently at version 6.3.1. It provides memory state management and card scheduling for spaced repetition systems. Released on a monthly cadence.

ai-ml

pip install fsrs

github ↗homepage ↗

INSTALL

IMPORT

SIG · FSRS

fsrs

ai-mlpythonv6.3.1

harness data pending

Install & Compatibility

Where this runs

No compatibility data collected yet for this library.

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

Card

✓ from fsrs import Card

✗ from fsrs import FSRS

Scheduler

✓ from fsrs import Scheduler

✗ from fsrs import FSRS

Rating

✓ from fsrs import Rating

✗ from fsrs import FSRS

Initialize FSRS, create a card, review it with rating, and print the next due date.

from fsrs import FSRS, Card, ReviewLog f = FSRS() card = Card() now = datetime.now() scheduling_cards = f.review_card(card, Rating.EASY, now) print(scheduling_cards.card.due)

Debug

Known issues

breakingIn v6, the FSRS constructor requires parameters; the old default-less constructor is removed.

fix

Use FSRS(parameters=...) or pass parameters explicitly.

affects: >=6.0

breakingIn v6, the `review_card` method signature changed; it now requires `rating` and `now` arguments.

fix

Call `f.review_card(card, Rating.GOOD, datetime.now())` instead of old style.

affects: >=6.0

gotchaThe `Rating` enum values are integers (0-4); pass `Rating.GOOD` or use integer directly.

fix

Use `from fsrs import Rating` and then `Rating.GOOD` for clarity.

affects: all

deprecatedThe `FSRS.review_log` parameter `review_log` is deprecated; use `review_card` with review log as an optional argument.

fix

Pass review_log as keyword argument: `f.review_card(card, rating, now, review_log=log)`

affects: >=6.0

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Version history

6.3.1latest on PyPI · released Mar 10, 2026

Audit

Dependencies

No dependency data recorded yet.

Agent activity

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Resources

githubhttps://github.com/open-spaced-repetition/py-fsrs ↗

homepagehttps://github.com/open-spaced-repetition/py-fsrs ↗