Build a workout tracker app for the gym floor

Design for the moment between sets

The logging screen is the product. Everything about it should be reachable with a thumb and readable at arm's length:

Last session's numbers beside each set, so you know what to beat without looking anything up.
Pre-filled weight and reps from last time, so a repeat set is one tap to confirm.
Large steppers for weight (in the increments your plates allow, such as 2.5 kg) and reps, rather than a keyboard.
A rest timer that starts when you log a set, with a visible countdown and a short sound when it ends. Make the default per exercise: longer for heavy compound lifts, shorter for accessories.
A screen that stays readable: high contrast, big type, and no tiny icons.

The data model

Getting the structure right early saves rewriting later. A workout log usually needs:

Exercises: Name, type (weight and reps, bodyweight reps, time, distance), default rest, and notes on form.
Routines: Named templates such as Push, Pull, Legs or Full body A, each an ordered list of exercises with target sets and reps.
Sessions: A date, the routine used, and for every exercise a list of sets: weight, reps, and optionally effort (RPE) or a warm-up flag.
Personal bests: Derived from sessions rather than stored by hand: heaviest weight, most reps at a weight, best estimated one-rep max.

For estimated one-rep max, the Epley formula (weight × (1 + reps ÷ 30)) is a common choice. It's only an estimate and becomes unreliable at high reps, so label it as such and consider ignoring sets above about ten reps.

Charts that show real progress

A chart of top-set weight per session is easy to read but misleading when rep counts vary. Better options: estimated one-rep max over time per lift, total volume (sets × reps × weight) per week per muscle group, and a calendar of training days. Keep charts on their own screen; the logging screen should stay uncluttered.

Asking Anticode for it

Describe your training style and the screens: "A workout tracker for strength training. Routines I create (Upper A, Lower A, Upper B, Lower B), log sets with weight and reps pre-filled from last time, a rest timer that starts automatically (3 minutes for squats, deadlifts and bench, 90 seconds otherwise), personal bests, and charts of estimated one-rep max per lift. Kilograms, 2.5 kg steps. Dark, high-contrast, one-handed."

The model writes the tracker as one app, with the timer sound made in code and the charts drawn in the page. Publish it, then install it on your phone's home screen: every published Anticode site can be installed as an app with its own icon and an offline fallback, which matters in a basement gym with poor signal; test it there before you rely on it.

Where the log is stored

Anticode apps run with no network, so your sessions are saved in your phone's browser and nowhere else. They survive closing the app and restarting the phone, but not clearing the browser's site data. Ask for an export button so you can download your history as a file now and then; keep it somewhere safe, and import it if you change phones.

What it won't do

No wearables. It can't read heart rate, steps or calories from a watch or a phone's health app.
No GPS. The sandbox has no location access, so it can't map runs or rides; log distance and time by hand.
No cloud sync. Logging on your phone and viewing on a laptop won't show the same data.
No coach view. A personal trainer can't see a client's log, because nothing is shared. Trainers who want that need a multi-user tool, or the Next.js export as a developer's starting point.
No programme advice. It records what you do; it doesn't judge whether a programme is right for you.

Questions people ask

Can a workout tracker app built this way work offline?

Once loaded, logging doesn't need the network, and every published site has an offline fallback. Test opening it offline before you rely on it.

Can I track cardio too?

Yes. Ask for exercise types measured in time or distance, such as rowing for 2,000 metres or a 30-minute ride, entered by hand.

Can I share it with friends at my gym?

Share the link and each person gets their own empty log on their own phone. There's no shared leaderboard.

Does the timer work with the screen off?

Browsers may pause a page that isn't visible. The timer can catch up from the clock when you return, but don't rely on the sound playing with the screen locked.