How it works
Type it in. It keeps the record.
Under Pressure does not touch your cuff. You read the figures, you file them, and the app holds a clean, dated series you can hand to a clinician.
01
Take a reading
Use your own validated cuff, the way your clinician showed you: same time of day, seated, rested.
02
Type the figures in
Enter systolic, diastolic, and an optional pulse. The date and time default to now; change them if you are filing an older reading.
03
File it by date
The reading joins a dated series in the same columns as every other, so a change reads as a change and nothing else.
04
Export a series
The clinician summary lays a period out as a one-page document or as CSV. Where it goes is up to you and the share sheet.
Same figures, same columns
A transposed digit reads as a shape change.
Every figure is set in tabular mono, so 128/84 and 98/61 share a column. Nothing is coloured to mean anything: the figures are the record, not a verdict.
Today
How it is built
The core is Rust. So is this page.
The part of the app that holds your readings is a Rust library, and the page you are reading was written out by a Rust program. One language at both ends, for the same reason: a mistake in the types stops the build, and never reaches your phone.
The core
Readings, the database, the statistics, the guideline bands and the export live in one Rust library. It knows nothing about Android, and every call into it returns a result instead of crashing.
The shell
The screens are Kotlin and Jetpack Compose. They draw what the core hands them and hand back what you type. The two sides talk through bindings generated from one definition, so both see the same types.
This site
These pages are Rust too: components written out as plain HTML once, at build time. No framework runs in your browser and no server has to stay awake. The site's tests read the app's own files, so the band words, the guideline edition, the Android requirement and the changelog here cannot drift from the app.
Under Pressure is not a medical device and does not diagnose, treat, cure, or prevent any medical condition.
