A constraint solver over the 138 courses of the Johns Hopkins electrical and computer engineering master’s: prerequisites, degree rules and the five-year clock, checked as you drag courses between terms.
A training model for military fitness tests. Sessions in, a predicted score out, and the cost of a goal by a date. The data is mine, so it asks you to sign in.
The days between two dates, a date plus or minus a span, and countdowns the alarms app on my phone shows too.
A social app for dog owners: matches by distance, packs with a shared feed, and playdates on a calendar. Live, with a demo account.