Caffeine CurveSee the caffeine in your system right now, and when it clears.
Every drink decays on a live half-life curve, so you always know your current level, when you'll be clear, and whether that 4 PM cold brew will wreck your sleep.
Free for iPhone · No ads · No accounts · No subscriptions
You have
141mg
Safe for bedtime · clears around 9:40 PM
Live level
What's in your system, live
Not what you drank today, but what's in your bloodstream right now. Every logged drink decays on a live half-life curve, updating every minute. A 12-hour projection chart lets you scrub into the future, and the subtitle tells you exactly when you'll be clear.
The number is an estimate from a tunable half-life model, not a medical measurement.
Sleep protection
Warned before it wrecks your sleep
Set your bedtime and a threshold. Before a drink is even logged, Caffeine Curve projects your level at bedtime. If that 4 PM cold brew would leave you over the line, you get the exact projected number first. An optional notification tells you the moment you're clear.
Heads up 🌙
Cold Brew (16oz) now would leave 87 mg in your system at your 10:30 PM bedtime, over your 50 mg threshold. This may affect your sleep.
One-tap logging
Log in one tap, from anywhere
Quick Log keeps your five most-used drinks one tap away. Twelve built-in presets, your own custom drinks, and retroactive logging for that coffee an hour ago. Home-screen and lock-screen widgets log without opening the app, and “Log a Drink” works from Siri and Shortcuts too.
Private by design
Your data never leaves your phone
100% on-device. No account, no server, no analytics, no tracking, no network calls. The App Store privacy label is simply “Data Not Collected.” Optional write-only Apple Health sync and CSV export keep your data yours.
0
data collected
0
trackers
100%
on-device
Your week at a glance
7-day and 30-day history with average, peak, and streaks
Tuned to your metabolism
Half-life presets from fast to slow, plus sleep settings
Ready in seconds
No sign-up. Log your first drink and go
FAQ
Questions?
How accurate is the number?
It's an estimate from a half-life model. The default is 5 hours, and you can tune it to your metabolism in Settings.
Is it really free?
Yes. Free, with no ads, no accounts, and no subscriptions.
Where does my data go?
Nowhere. Everything stays on your phone. There's no server to send it to.
Love coffee. Love sleep. Keep both.