Create a four-choice multiple-choice quiz from your own problem set that you can memorize

An app (iPhone) that turns what you want to remember into multiple-choice questions to create your own personalized problem set. Problems you've solved appear again when you're likely to have forgotten them, so you can continue studying for certifications and memorizing vocabulary a little bit each day.

・Creating, solving, and reviewing problem sets are free. No limits on the number of sets or problems.
・Each time you answer correctly, the interval until the next appearance extends: 1 day → 3 days → 7 days → 14 days → 30 days → 90 days
・Review notifications and a widget showing today's review count
・iCloud sync. Export with the same CSV format as the Web version's "My Problem Sets"
・No account registration required

Pro (500 yen per month, free for the first week) unlocks: drafting problems from photos, problems with images, learning analytics, automatic backups, and CSV import from the Web version. Ads are also removed.