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The SM-2+ engine behind every review queue

Spaced Repetition

Cards resurface at the scientifically optimal interval, weighted by your confidence ratings and live performance — the memory engine powering Learn mode.

Free

The memory engine under everything

Spaced repetition is the platform's core scheduling algorithm — SM-2 and above — built into every review queue and powering Learn mode. Cards resurface at the scientifically optimal interval for long-term retention, but ours goes beyond a fixed schedule: it weights each card by the confidence you rate before flipping it and by your live performance in sessions like FastFire. The result is a queue that spends your time on what you're about to forget, not on what you already know cold.

Smarter than a fixed schedule

SM-2 and above

The proven spaced-repetition algorithm family, built natively into every review queue across the platform.

Confidence-weighted

Rate how sure you are before you flip — that signal feeds straight into how often the card comes back.

Performance-aware

Live results from study sessions re-weight intervals, so a card you just bombed resurfaces sooner.

Powers Learn mode

The same engine drives the adaptive Learn session, continuously reshuffling toward your weakest items.

Study it now

Master Spaced Repetition with AI Matrx

Generate flashcards, quizzes, and audio from your own notes — then study with an AI tutor that knows exactly where you're stuck.