Whenwhat is an app that makes it super simple and super quick to schedule email reminders. Just enter a subject and a time and tap follow up, and you will receive an email at a certain time. You can choose a certain delay, for example 5 minutes, 2 weeks, or 1 year. You can also select a specific day of the week, for example next Wednesday, or a specific time and date.

The app is designed for fast scheduling with a minimum of taps. If you think of something in the morning that you want to remember in the evening, just enter the subject, delay it with 8 hours and forget about it until you get reminded.

You can use it for many many things, for example:

- remind you of a phone call you must do later
- remind you of something you should buy
- remind you of a subscription you must renew
- remind you of a subscription you must cancel
- remind you of someone's birthday

The app works together with the free email reminder service followupthen.com. Premium users of followupthen.com can also receive sms-reminders.