It started on CodePen. I built a small tool to manage my sets at the gym: rest timer, exercise tracking, nothing sophisticated. I posted it, forgot about it, and it kept growing on its own. Today it sits at around 39,000 views and 250 likes. That number stuck with me.
The original frustration was simple. I went to the gym regularly and could not find a single app that handled rest times between sets properly without being either too basic or too heavy for performance tracking. The CodePen project solved my own problem. The fact that others used it that much confirmed the need was broader.
The conversation that changed things
About three years ago, I got in touch with an independent sports coach. He was using a client management solution I found genuinely hard to use: confusing interface, unclear workflows, not adapted to the day-to-day reality of a coach following several athletes at once.
I thought there was clearly something better to build. I had the skills, I had the context, I wanted to do it. The project sat in my head for a long time before I finally decided to actually build it.
What I Train With You does
The application is built for independent sports coaches, not gyms. The ones who work with clients one-to-one, in person or remotely.
Coach side: they can create session modules (workout templates), schedule them with their clients, and track progress in real time. They can also share nutritional guidance, which stays in the realm of advice rather than prescription, but it centralizes the useful information in one tool instead of juggling Google Docs and WhatsApp messages.
Client side: they receive their programs directly in the mobile app, follow sessions with rest times configured per exercise, and can review their history. If they do not have a coach, they can also use the app on their own: build custom sessions from an exercise library, set goals, track their sets.
The model is freemium. Clients access the essentials for free. Coaches get a functional free tier, with paid plans as their client base grows.
Stack and development environment
On the technical side, I stayed with what I know: AdonisJS for the backend, React Native for mobile. These are technologies I used for several years in previous roles, which means I am fully autonomous on everything from database schema to deployment.
I also set up local test servers at home, on my homelab. That let me learn how to configure routers, reverse proxies, and access security. Time invested upfront, but also a way to test in near-production conditions without paying cloud infrastructure costs during development.
A significant part of the code is generated with AI assistance, which speeds up production considerably. But it does not replace understanding what is being generated. AdonisJS and React Native both have their specifics, and being able to read and correct AI output is still essential.
What comes next
I Train With You is in alpha. I will post articles as the project progresses: technical choices, problems encountered, feedback from early users. The project is active and evolving.
Check it out at itrainwithyou.com or get in touch if you are an independent coach looking for a tool like this.