An early Replit Agent experiment: a workout tracker with an exercise library, templates, sets and reps, a rest timer and workout history, modelled on an iOS gym app.
One of my first real goes at building with an agent, back in February 2025. I wanted a workout tracker, so I showed Replit Agent screenshots of an iOS gym app and asked it to match them.
It got to a working app with an exercise library, workout templates, live set and rep tracking with a rest timer, and a history of finished workouts.
Most of my steering was testing. The commit history is the agent asking me to click Start Workout, add an exercise, log a few sets and tell it whether the server had crashed again. I learned to push it to fix stability before adding features.
React on the front, Express on the back and Postgres through Drizzle, all inside Replit.
Not very far, and that's the lesson. Agents in early 2025 needed a lot of hand-holding and kept falling over. It's useful to look back at how much has changed in a year and a half.
This started in February 2025. I gave Replit Agent screenshots of an iOS gym app and asked for a tracker that worked the same way: an exercise library, a profile, an exercise detail page and a workout screen with sets, reps and a timer.
The history reads like a conversation with a nervous junior developer. “Can you try clicking Start an Empty Workout and let me know if the workout page loads?” “I notice the server keeps crashing. Should I fix that first?” Yes, it should. I came back in March and April for templates, starting and finishing workouts and a proper history.
It worked. There are no screenshots because the app only ran inside Replit and the reference screens belong to someone else’s product. I’ve kept it here as a marker of where I started.