When I said the Android app was coming, I said reminders would come first. They're in now. Deciding how they should work took me longer than building them.
My first idea was a reminder the day before each to-do. Then I looked at my own to-dos for my next trip. They all have a date and no time, and some days have three. Three buzzes for things I'd happily read in one go felt like the wrong side of the line between useful and annoying.
So the main thing is a morning brief. Around 8 you get one notification with what's due today and tomorrow. On a day with nothing due you get nothing. If something slips past its date you hear about it once, the next morning. And the day before a trip starts it tells you how many to-dos still have no date. One morning soon mine will say "Today: buy the bus tickets".
For the ones that can't slip, a to-do can also have its own reminder. Remind me starts at Never, and you can pick On the day, 1 day before, 2 days before, 1 week before or Custom for something like 3 days before at 9:00. A to-do with a time gets choices like 15 minutes or an hour before.
Android likes to hold reminders back to save battery, sometimes by up to an hour. That's fine for the brief, which is why it says around 8. For your own reminders the app asks once if it can use Alarms & reminders so they come on time. If you say no they still come, just not always on the minute.
It all runs on the phone. Reminders are set before you lose signal and go off anyway, so they work on a plane or up a mountain. Tapping one opens the to-do.
Remind me is only in the Android app, since that's what sends it. In Settings → Notifications you can turn off the brief or your own reminders, and move the brief to another time.
Still free, still one person building it. Coffee pays for the server your trips sync to and the AI that reads your booking emails.