{"categories":[{"label":"Scientific/Engineering","url":"https://skillfed.io/packages/category/scientific-engineering/7"}],"enrichment":{"capability":"Implements the Free Spaced Repetition Scheduler algorithm to calculate optimal review intervals for flashcards and study materials based on memory retention science.","skillfed_tags":["spaced-repetition","learning-algorithm","study-tool"],"use_cases":["Build a custom flashcard app or study tool that automatically schedules reviews based on memory science rather than fixed intervals.","Optimize FSRS parameters for your own review history to improve scheduling accuracy for future study sessions.","Integrate spaced repetition scheduling into language learning, exam prep, or professional certification platforms.","Reschedule existing cards after parameter optimization to apply improved scheduling to your current deck.","Calculate and monitor card retrievability (recall probability) to decide when to prioritize urgent reviews."],"what_it_does":"Py-FSRS is a Python implementation of the Free Spaced Repetition Scheduler algorithm, which calculates when to review flashcards or study materials to maximize long-term retention. It models memory decay and uses a set of 21 tunable parameters to predict the optimal time to show each card again\u2014balancing review frequency against forgetting probability. The package provides core classes (Scheduler, Card, Rating, ReviewLog) for building custom spaced repetition systems, with JSON serialization for persistence and network use.\n\nThe scheduler tracks three card states (Learning, Review, Relearning) and four rating levels (Again, Hard, Good, Easy), adjusting intervals based on your desired retention rate (default 90%). It supports customizable learning steps, relearning intervals for lapsed cards, and optional parameter optimization if you have historical review logs. All timestamps use UTC, and the package includes retrievability calculation to estimate the current probability of recalling a card.","worth_installing":"Yes. The package is actively maintained, has low install friction, carries a permissive MIT license, and solves a well-defined problem (spaced repetition scheduling) with a proven algorithm. It's suitable for anyone building a study or flashcard system. Install it if you need scheduling logic; skip it if you're using a pre-built flashcard app."},"id":"fsrs","links":{"html":"https://skillfed.io/packages/fsrs","md":"https://skillfed.io/packages/fsrs.md","pypi":"https://pypi.org/project/fsrs/"},"maintenance":{"status":"active"},"meta":{"latest_release":"2026-08-09","license_spdx":null,"license_treatment":"permissive","name":"fsrs","python_support":"supports_current","summary":"Free Spaced Repetition Scheduler"},"popularity":{"monthly_downloads":129257,"position":11677,"tier":"top_15000"},"security":{"n_vulnerabilities":0},"version":"6.3.2"}