Log one in seconds, even mid-attack with one eye shut. See what is actually going on over weeks and months. Keep every bit of it on your phone.
That is precisely what a person mid-migraine cannot look at. HeadSense is a dim room with one soft green light, because narrow-band green is the part of the spectrum that does not make photophobia worse. The control above is the same one that sits in the app's settings. Mercy should be one tap away, not buried in iOS Settings.
Big targets, one thumb, no forms to fill in before the pain is recorded. Update the intensity later from the Lock Screen, without opening the app or raising the brightness.
Frequency over weeks and months, triggers, time of day, and which medications actually helped. Laid out plainly, with the numbers shown.
A headache is a mark on the page, coloured by how bad it was. A month of them is a shape you can read at a glance, without a chart to decode first.
Weekly and monthly reports are counts, frequencies and comparisons over what you logged, worked out on your phone. No server, no model, no guessing. Every figure is one you could arrive at yourself with the entries in front of you, and the report shows its working. Export one to take to an appointment.
HeadSense used to charge for its reports, because they ran on a server that cost money every month. They are arithmetic now, and arithmetic runs on your phone for free. So there is nothing left to charge for. There is a tip jar in Settings if you want one, and it unlocks nothing.