A client app for your gym or personal training business

A gym, studio or personal trainer can have a client app with a class schedule, bookings and waitlists, QR check-in, per-client workout programs and progress logs, by describing it to App Builder Agent. An AI agent writes the code, shows a phone preview in the browser, and you refine it by describing changes. A first version fits within the Free plan (500K AI tokens a month; free APK download); unlimited builds and source export are $1.49 per 30 days on the Member plan at the time of writing. Membership payments stay on the payment page you already use; the app tracks status and expiry.

Small gyms and independent trainers in the US, UK, Canada and the EU mostly run on a booking SaaS, a spreadsheet of programs and a WhatsApp group. Each works, and none of them feels like the business. A client app with your name on it puts the schedule, the programs and the check-in in one place on the member's phone, and gives you a member list that is actually yours. This guide covers what the app needs, the prompt to paste, what the first minutes look like, getting it onto phones, and costs.

What the app needs

Two roles share one hosted backend: members (or clients) and the owner/trainer. A studio with several coaches adds a coach role later.

• Class schedule with capacity. A week view, each class with a time, coach, room, capacity and level. Members book, cancel until a cut-off, or join a waitlist that promotes automatically.
• Check-in. A QR code in the member's profile that the desk scans, or a self check-in button that only works within a distance of the gym. Attendance history per member.
• Membership status. Plan name, start and expiry date, sessions remaining for pack-based clients. A reminder seven days before expiry.
• Workout programs per client. The trainer builds a program (exercises with sets, reps, weight, rest, notes, video link) by day and assigns it. The client logs sets from the app during the session.
• Progress logs. Weight, measurements, personal bests, progress photos, with a simple chart per metric. Only the client and their trainer can see them.
• Announcements. "Saturday 9 am spin is cancelled", "new timetable from Monday", sent as notifications.
• Owner dashboard. Today's classes and bookings, members expiring this month, no-shows, attendance by class, CSV export.

The consumer side of this, workout logging and timers for a person training alone, is covered in a fitness and workout app without coding. The business app here is that plus the schedule, the roles and the member list.

The prompt to paste

Open the AI app builder, sign in with Google, start a mobile app project and paste this with your own timetable:

Give the real timetable and the real class names. The agent uses them as seed data, and the first preview shows your actual week, which is the only way to judge whether the schedule screen reads well on a phone.

What you get in the first minutes

The agent writes the app in React Native, deploys the hosted backend (database, sign-in, file storage on the platform's servers) and shows the member app in a phone-shaped preview. Book Tuesday's 6 pm Strength class, book it from a second test member until it is full, and confirm the thirteenth goes to the waitlist. Switch to the owner login, cancel the class, and check that both members receive a notification and their bookings disappear.

Then refine in plain English: "show the coach's photo on each class", "the log screen needs a rest timer that counts down after each set", "progress photos should be private to the member and their trainer only", "add a 'freeze membership' action for the owner". Expect each small change to land in under a minute. Two rules worth stating early: bookings are confirmed by the backend only if a spot is still free at the moment of saving (two phones tapping at once should not overbook), and class times are stored in UTC and shown in the gym's time zone so daylight-saving changes do not shift the timetable.

Getting it onto phones

The front desk tablet and your own phone get the APK first: Download APK from the preview, install directly, no Play Store. Then the members: put the download link in a QR code at reception and in the welcome email. Installing from a link takes one confirmation on Android; installing an APK on Android covers the screen people ask about.

For a Play Store listing, ask for a signed store build. The builder generates and encrypts a signing key for the project and produces a signed APK and AAB with your own package id and an auto-incrementing version code. As of 2026, a Google Play Console account costs a one-time US$25 with identity verification; new apps upload as AAB; every app needs a privacy policy URL and a Data safety form; and personal accounts opened after November 2023 must run a closed test with at least 12 testers for 14 days before production. A gym has a ready supply of testers. The full sequence is in publishing on Google Play from the US, UK or EU.

iPhone members use the web version of the same project at a link on appbuilderagent.com, added to the home screen from Safari. A native iPhone app means exporting the source on the Member plan and building with Xcode or Expo EAS on a Mac, plus the US$99 per year Apple Developer Program.

What it costs

At the time of writing: Free is 500K AI tokens a month with every feature and no card; a free APK download is included. A member app of this size is typically a few hundred thousand tokens to build and adjust, so the first version fits. Member is $1.49 per 30 days (roughly £3.90 or €4.50) for 5M tokens, unlimited builds and source export; Pro is $5.72 per 30 days for 10M tokens for owners who change the timetable and programs every week. There are no per-member fees. Prices can change.

For comparison, gym management SaaS in the US, UK and EU commonly lists plans from a few tens to a couple of hundred dollars, pounds or euros a month, often tiered by member count; a custom app from an agency runs roughly US$20,000 to $150,000 or more. How much it costs to build an app compares the routes side by side.

Notes for the US, UK, Canada and the EU

• Health data is sensitive. Weight, measurements, injuries and progress photos are health-related data. Under GDPR and UK GDPR that means explicit consent and tighter handling; in the US, state privacy laws such as California's CCPA/CPRA also cover it. Keep progress data visible only to the client and their trainer, ask for consent at first use, and offer an export and a delete button. General information, not legal advice; a privacy policy for your app covers the notice.
• Waivers. US and Canadian gyms typically collect a liability waiver; UK and EU studios usually collect a health questionnaire (PAR-Q). Either is a one-screen form the agent can add, signed once and stored on the member's profile.
• Prices and tax. US memberships show tax separately where it applies; UK and EU prices include VAT; Canada adds GST/HST. Since payment happens on your existing page, the app only needs to display the price the way your region expects.
• Cancellation rules. UK and EU consumer rules on subscription cancellation are stricter than most US states; showing the membership end date, notice period and a "cancel" request button in the app avoids disputes.

Tip: Assign one real program to one real client before you invite everyone. A week of logged sets will show you exactly which fields the log screen needs (most trainers cut half of them), and the change is one sentence to the agent.

To see what finished results look like, browse the fitness apps in the gallery. The same booking mechanics in a different trade are in a salon and barber booking app, and the general playbook for any small business is in an app for your small business without hiring a developer.

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