SYRE

Personalized HIIT Workout and Pilates

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Inspiration

During the pandemic I was doing plenty of home workouts by following HIIT workouts on YouTube. But I eventually reached a point where I had to repeat the same workouts I liked multiple times, and then found myself spending a lot of time searching for a different workout that fit my expectations well enough to keep things interesting and challenging, or got tired of waiting for my favorite fitness influencers to release a brand new workout video because I had started getting bored of looping through the same ones. Realizing it just took too much time to constantly find something that was meant for me and interesting enough for me, I came up with this HIIT Builder app idea, where every single workout is curated and wired to the user's own capabilities and attributes, and the fully crafted workout plays out in the style of a high-production YouTube fitness influencer video, so that I wouldn't have to seek out that coolness elsewhere when I mirrored the workout onto my TV, with some cool music in the background and sound cues of course, while keeping track of everything I do, even counting calories. I finished the first prototype back in mid 2023, but then, due to real-life obstacles, I stopped development. Now, thanks to AI and more time on my hands, I decided to basically rewrite the entire thing in early 2026. The first couple of months were exhausting due to the real-life shooting of 450+ exercise videos with an expert I partnered with. I even had to shoot some of those exercises myself! By the time I learned about Shipaton, the app was mostly in a usable state, but I sped up and finally released it in mid September in a way that satisfied my perfectionist nature.

What it does

This app is for people who don't have time for the gym or simply don't like gyms (like me), and want to get in shape in the most efficient way possible while keeping their cardiovascular health at its peak. It basically provides a workout wizard that you go through step by step to generate a workout from our 430+ unique exercise catalogue, all real videos performed by real trainers, and then plays the workout in the neatest way possible, so that it feels like you are watching a workout from one of your favorite fitness influencers. The app keeps a record of these workouts, saves each session to Apple Health, counts your streaks if you have any, and gives you all sorts of statistics such as total workout time and total calories burned, which can be calculated accurately if you wear an Apple Watch during the workout. You can save your favorite sessions to perform them any time later. There are also professional presets, either crafted by professionals or inspired by their workouts that have proven to produce amazing outcomes. SYRE Coach, which is Premium only, is where AI generates a workout based on your body statistics and attributes. You can still tell it what kind of workout you want, and the AI will give you something you are definitely capable of doing at your fitness level.

We also have a Courses section where you can access a wide variety of expert-specific knowledge on a sub-branch of any kind of fitness. These courses are going to be one-time purchases, and they are made to add something you never got to know before, whether it's bodybuilding, Pilates, yoga, etc.

How we built it

SYRE is a React Native app with a Supabase backend. Supabase handles sign-in (you can start as a guest and link Apple or Google later without losing anything), the exercise catalogue with its muscle maps and tags, music storage, and the edge functions that do the sensitive work.

SYRE Coach is one of those functions, sitting in front of Google Gemini. The app never sends free text, only the options you picked, so nobody can inject a prompt. The server writes the prompt, shuffles the exercise list so results stay fresh, and checks every answer before it reaches you: banned moves out, left and right sides paired, gaps filled, recent sessions remembered.

Exercise videos are downloaded to the device on Wi-Fi so workouts play offline. Course videos stream from Cloudflare Stream with signed links and subtitles.

RevenueCat runs the money side. Subscriptions come from one offering with monthly, 3-month and yearly packages, and each course is a non-consumable bought by product id. We use the same id for the Supabase user and the RevenueCat customer, and we log in before every purchase or restore, so a guest who signs in later keeps what they bought. Entitlements gate play, saving, the Coach and each course inside the app. For course videos we don't trust the client: a RevenueCat webhook keeps an entitlements table in Supabase up to date, and the function that signs a video link checks that table first. Ads for the free tier run through AdMob and report back to RevenueCat, so ad revenue and purchases live in one dashboard. The RevenueCat Test Store let us test all of this in the simulator.

Around that: Apple Health sync, reminders, lock-screen music controls, crash reporting, certificate pinning, and nine languages.

Challenges we ran into

Back in 2023, while I was working on the first prototype and AI wasn't a big thing yet, I couldn't decide how to handle the AI part of the app. Because I was doing everything myself with no assistance, I noticed I was wasting a lot of time on certain details I couldn't get out of. I wanted to integrate an SLM (Small Language Model) that works directly on your device, locally, so that no user-specific info would go anywhere and it would stay private. I wanted this confidentiality to set my app apart, but SLMs were not advanced enough at that time (they still aren't, at least not for what I had in mind), and the backend side was another dilemma: I wanted everything on AWS, but I had neither the technical depth to do it all nor the time. So I paused development for almost 3 years, only to rewrite everything in early 2026 for this competition.

Accomplishments that we're proud of

I'm proud of the end result. A fitness app capable of generating dynamic, unique workouts in which the exercises are actually performed by real people instead of some GIF elevates the experience to what I had imagined back in 2023. I'm aware there are apps that do the exact same thing, but in my opinion they are not as good in terms of UX. My workout player has a UI that matches the layout of those YouTube workouts, and generating a workout is much more straightforward while still being extremely in-depth. You never lose yourself in the app not knowing what to do next; it's made to be intuitive that way.

As a mobile engineer who's been doing this for 10 years, I can gladly say this is actually one of the most technically complex apps I've ever worked on, if not the most complex. The animations and effects I added here were something I had never had to do before.

What we learned

I got to experience what it means to have Supabase as your all-in-one backend solution, RevenueCat to handle all subscriptions and IAPs, and Cloudflare as the storage and streaming service for all exercise videos, and for the first time ever I got to add AdMob to a mobile app. Wiring all of these into one app and dealing with all the bureaucracy with Apple, Google and the rest was quite challenging. Now I know exactly what an app with these kinds of attributes needs to have, and shouldn't have, in order to be accepted by Apple and Google. Despite having released multiple apps to the stores as an engineer for the companies I worked for before, this one taught me plenty of new things I never got to learn at my past companies.

What's next for SYRE

Recently I received a couple of pieces of user feedback, so I want to work on them and release them as 1.0.1 along with the second course in the app. But my real goal is to partner with as many experts as possible and sell their courses through my app, with no limit to the type of fitness (there could be a course on elite bodybuilding, advanced reformer, yogalates, etc.), so that I can reach a wider audience. I also plan to add live-streamed group workouts and create an ecosystem where fitness influencers can sell their own ebooks or fitness plans through my app. I want to make this thing much bigger than it currently is.

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