Remember more words with less effort. Words on Repeat uses the FSRS algorithm — the most accurate spaced repetition scheduler — to show you each word at the right moment.
The most accurate open-source spaced repetition scheduler, backed by peer-reviewed research. FSRS learns how you remember each word and schedules reviews at the optimal moment.
Organize vocabulary into language decks. Duplicate decks, share them with other users, and switch between decks from any page.
Paste words from AI assistants like ChatGPT or Claude, upload JSON files, or use the API to add vocabulary automatically. Duplicate detection keeps your decks clean.
Track your retention rate, daily reviews, due forecast, study time, and streaks. See detailed memory metrics for every card.
Works on any device — no app install needed
Export your data anytime — nothing is locked in