A shoutout to SuperMemo here - one of the oldest SRS out there. Their first version was on Amiga, if I remember correctly, and the newest ones support iOS, use LLMs and all the other tech :)
iOS? No, certainly not. The recently released version just did the jump from Internet Explorer to Edge support.
You probably mean the confusingly identically named SuperMemo on supermemo.com (not .guru), that is indeed a spaced-repetition software, but is not the venerable and famous real SuperMemo with a gazillion of features and research behind it. Just a simplistic knockoff. Strangely by the same author.