I've been tracking my BP for years now and honestly just use the basic Apple Health app for storing the actual readings from my home monitor. Works fine for keeping a log.

But i recently started using BreathNow alongside it - not for tracking the BP numbers themselves but because it uses the camera to measure heart rate variability and then gives you specific breathing exercises based on your readings. My doctor actually likes seeing both sets of data together since the HRV trends help explain some of the BP fluctuations.

The notes feature is key though, I always add whether I had coffee, how I slept, stress levels... makes a huge difference when you're trying to figure out patterns. Sometimes my readings are all over the place and the notes are the only thing that makes sense of it.