# Your Stressy > The battery your body never had. A clean and fun UI & UX for iPhone/Apple Watch. - **Website**: https://stressy.ervo.rocks/ - **Uneed Page**: https://www.uneed.best/tool/your-stressy - **Pricing**: Paid - **Category**: Personal Life - **Tags**: Habits, Fitness, Health - **Submitted by**: @ervorocks - **Launch Date**: 2026-11-07 - **Social Links**: [Instagram](https://www.instagram.com/yourstressy/) ## About Your Apple Watch measures your sleep, heart rate and HRV all day, but never tells you the one thing you want to know, how much energy you have left. Stressy turns it all into one fun number, your reserve, from 0 to 100%. $4.99 once, never a subscription, and your health data never leaves your iPhone and Apple Watch. More details about all of this below. Your Stressy is an app with a super clean and fun UI/UX (Swift, Liquid Glass and more), crazy haptics, and 120 Hz ProMotion optimization, made for iPhone and Apple Watch. I've analyzed Apple developer documentation in details to find fun and more hidden APIs that could potentially improve the UX, this is actually how I figured it out the CADisableMinimumFrameDurationOnPhone configuration flag. What it does? Using your Apple Watch's sleep tracking, it gives you battery-like feedback on your health stats through the day: one number, your reserve, from 0 to 100%. On top of that you get readiness for training and bedtime coaching, Body Age, Vo2 Max Estimation (Not Apple Health estimation) with great and configurable charts for your reserve and stress. Many of the charts are available as widgets too for both iPhone & Apple Watch. New in 1.4 • Your own VO₂max: Stressy now calculates your Cardio Fitness itself, from the pace of your runs, walks, hikes and rides and how hard your heart worked, against your own maximum. Not Apple Health's estimate, which reads low in independent lab studies. Every step of the math is shown. • Fitness Test on Apple Watch: five easy minutes to warm up, then run as far as you can in 12 minutes, guided by taps on your wrist. • Workouts counted in full: sprints and stop-and-go sports count at their real effort, and on the stress chart and widgets each workout shows in its own colour, with how hard your heart worked. • Nights, hour by hour: after a late night your sleep recharges with your heart, slowly while it's still racing and fully once it settles. • Theme: Light or dark, your choice, instead of only automatic, can be configured in Settings. • More stuff: Many sleek widgets available for both iOS & watchOS, for stress (3 different designs so it's customizable), steps, distance, battery, sleep, and much more to come soon in the next releases, I have 1+ year of roadmap features, including offline and on-device AI features by using Apple Foundation models. Also since launch Body Age (how old your fitness and habits look), a layout optimized made for iPhone Duo, steps and distance hour by hour, every stage of your sleep, every workout with its route on a map, and story videos/photos for Instagram made right on your iPhone. Since launch Stressy already has been purchased by many people, so far the reviews are all positive and visible on App Store page based on country. I hope you enjoy it. How it calculates? The whole calculation algorithm is custom made. The data comes from Apple Health: sleep, HR, RHR, HRV and other parameters go into the formula that calculates your stress, battery and readiness. Everything is calculated on your iPhone and Apple Watch, and your health data never leaves as there is no requirement for any backend, this is all stated of course as part of the App Store page. Price A fixed price of $4.99. I personally don't like in-app subscriptions, and I think a one-time payment is the fairest option, so Stressy will never have a subscription. Already shipped many paid features as an update to the existing app, and the roadmap is huge, my plan is to find the best and most precise algorithms for each feature and implement it as an update. In the next release I'll be adding the first AI feature for summarizing initially for sleep, and this AI feature will be completely offline and on-device by using Apple Foundation models. A bit of history, and how it was made, who am I A year ago, after 11+ years as a software engineer, I decided to slowly start learning Swift, these days it's so much easier to learn any programming language, the syntax which used to cost a lot of time, is now much quicker task. I always wanted to build native app experiences. as mainly a frontend person, we know that Flutter and similar frameworks can never get you to a fluid native experience. I've always paid lots of attention as Frontend engineer to the UI/UX which I think not everyone puts attention but are really important parts. If you have any feedback, positive or negative criticism, anything, I'm all ears. Thanks! Download on the App Store: https://apps.apple.com/app/your-stressy/id6822681002 Every feature and detail: https://stressy.ervo.rocks/ Who Am I: https://ervo.rocks/ Thanks, Ervo.