The best open source alternative to Quizlet is Anki. If that doesn't suit you, we've compiled a ranked list of other open source Quizlet alternatives to help you find a suitable replacement.
Quizlet alternatives are mainly Education Software. Browse these if you want a narrower list of alternatives or looking for a specific functionality of Quizlet.
Flashcard app using spaced repetition to schedule reviews at the exact moment you're likely to forget, so you retain more with less study time.

Anki is a flashcard app built around spaced repetition, a proven technique that schedules each card's review at the moment you're most likely to forget it. Instead of grinding through the same material repeatedly, you focus your time where it's actually needed. The result is stronger long-term retention with fewer study sessions.
It's used heavily by medical students, language learners, and anyone who needs to hold a large volume of information in memory. Decks can scale to 100,000+ cards without performance issues, which makes it practical for serious, long-term study rather than just quick cramming.
Key capabilities:
The scheduling algorithm is what sets Anki apart from simpler flashcard tools. Each time you rate your recall, Anki adjusts the next review interval. Cards you know well appear less often; cards you struggle with come back sooner. Over time, this compounds into genuine long-term memory rather than short-term recognition.
Anki is open source and community-driven. Add-on developers, deck creators, and code contributors all feed into the same shared ecosystem. If you're building a personal knowledge habit alongside tools like a read-it-later service or a quick-capture notes app, Anki handles the retention side of that workflow.