The spaced repetition that Mochi uses is very simple. Each time you recall a card during one of your reviews, the amount of days before it shows up for review again doubles. If you are unable to recall a card, the interval between reviews halves.
So, for example; the very first time you review a card, it will show up for review the next day. If you happen to recall the card, it will show up for review two days later, and so on.
The app can be used via the web or a download is available for Mac, Windows, and Linux. Best of all, the notes support Markdown, attachments, Latex, and more. If you have something you want to memorize give this app a try.