Caffy: Caffeine Tracker

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  Dashboard

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  Energy- Focus

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  Sleep Prediction

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  Choose a Drink

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  Pick a Size

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  Log - Day

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  Log - Week

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  Log - Month

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  Metabolism

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  Metabolism Absorption Phase

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  Insights

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  Insights - Weekly AI Analysis

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  Detox Mode

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  Widgets

Inspiration

I built Caffy because most caffeine trackers only tell you how much coffee you drank today. What I actually wanted to know was: how much caffeine is still in my body right now, and will it affect my sleep tonight?

That became the core idea behind Caffy.

What it does

Caffy tracks caffeine in real time using caffeine half-life models. Instead of simply counting cups, it estimates how much caffeine is still active in your body throughout the day.

It also provides a Sleep Readiness score, shows when caffeine is likely to peak, estimates how much will remain by bedtime, and lets you simulate a drink before actually having it.

The caffeine model can be personalized based on factors such as sensitivity, age, pregnancy, smoking, and oral contraceptive use.

How I built it

Caffy is a native iOS app built with Swift and SwiftUI.

The main challenge was turning caffeine pharmacokinetics into something understandable at a glance. I built a real-time caffeine decay model, then designed the UI around a simple visual gauge, charts, sleep predictions, and actionable insights.

I also added HealthKit integration, Home Screen and Lock Screen widgets, smart notifications, caffeine detox programs, and weekly habit analysis.

Challenges

One of the hardest parts was balancing scientific accuracy with simplicity. Caffeine metabolism varies significantly between people, so using a single fixed half-life would not be very useful.

Another challenge was presenting all of that information without making the app feel clinical or overwhelming.

Building Caffy has also taught me a lot about onboarding, subscriptions, App Store optimization, and what users actually understand when they first open a health tracking app.

Caffy is currently live on the App Store and I'm continuing to improve it based on real user feedback.

Built With

• apple
• charts
• healthkit
• ios
• supabase
• swift
• swiftui
• widgetkit