One photo a day, lined up against yesterday's, next to a true-vertical guide you drag into place yourself. No sensors guessing at your spine — just your own eyes, given a straight line to check against.
Free to start · Pro unlock is $2.99 once, never a subscription.
Plumb is a measuring tool, not a medical device. It does not detect posture, diagnose anything, or analyze your body automatically. It takes two photos, gives you a draggable plumb-line to lay over them, and lets you compare what you see with your own eyes over time.
What it actually does
Everything in Plumb is something you do — the app just holds the ruler steady.
An on-screen vertical guideline helps you frame the same shot the same way each day, using your front camera.
Drag two points onto any saved photo to draw your own straight reference line — you decide what "true" means for that photo.
Line up 2 check-ins for free, or up to 5 at once with Pro, to see change across weeks instead of guessing from memory.
A simple streak counter for consecutive check-in days — the only "score" in the app, and it only measures consistency.
One optional local notification at a time you choose — no server, no push infrastructure, just an on-device alarm.
No account, no cloud, no analytics SDK. Your check-in photos never leave your phone unless your own iCloud backup includes them.
How it works
Open Plumb, stand where you always stand, and use the on-screen guide to frame today's photo the same way as yesterday's.
Place two points on the photo to draw your own vertical reference — over an ear, a shoulder, a hip, wherever you want to track.
Pull up any two (or five, with Pro) check-ins side by side and look — really look — at how the line sits against you now versus weeks ago.
Inside the app
Plumb borrows its palette from the tool it replaces: a physical spirit level and plumb bob, not a hospital chart.
Today — streak & capture
Annotate — draw your own line
Compare — two dates side by side
Timeline — every check-in
Unlimited history, compare up to 5 dates, custom guideline colors.
Pro — one-time unlock
Settings — reminders & style
Pricing
Pro is a single non-consumable purchase billed once through the App Store — not a subscription, and it doesn't renew.