Prepaid session pack tracking for personal trainers

The idea

An independent trainer with 25 clients is running two dozen tiny prepaid balances in their head, a notes app, and goodwill. Sessions get trained and never counted; packs run to minus three before anyone mentions money; and the renewal conversation happens weeks late because nobody noticed the pack was empty. That is direct revenue leakage in the trainer’s core unit of business.

Mindbody starts around 139 USD/month and is built for facilities with front desks. The wedge is making the session-pack ledger the entire product: one tap after each session, a receipt that keeps the count honest on both sides, and a payment link that fires itself the moment a pack runs dry.

Who pays

Solo trainers renting gym floor space pay 15 USD/month from their own pocket. The auto-renewal link alone typically pulls the next 650 USD pack forward by weeks, which makes payback self-evident. Distribution: trainer Instagram communities, certification-body alumni groups (NASM, ACE, UK PT courses), and gym owners who host freelance trainers and want their renters solvent.

MVP scope

• Client roster with pack sales via logged payment or Stripe payment link
• One-tap session burn from a mobile-first dashboard with 10-minute undo
• Client email receipts showing sessions remaining after every burn
• Automatic renewal payment link when a pack hits the trigger threshold
• Append-only ledger with comp sessions visible
• Skip for v1: scheduling and calendars, workout programming, nutrition, group classes, client mobile app

Build PackCount, a web app that tracks prepaid session packs for independent personal trainers.

Stack: Next.js (App Router), Supabase (Postgres + auth), Stripe for client payments and trainer billing.

Core flow: the trainer adds clients and sells packs (for example 10 sessions at 650 USD), either logging an offline payment or sending a Stripe payment link the client pays online. Each pack is a ledger with a balance. After a session, the trainer opens the app on their phone and taps Burn Session on the client; the balance decrements and the client gets an email receipt showing sessions remaining, which quietly kills every did-I-pay-for-that dispute. When a balance hits zero (configurable to trigger at one remaining), the app automatically emails the client a Stripe payment link for a renewal pack and flags the client on the trainer's dashboard until it is paid.

Pages: mobile-first trainer dashboard with today's clients and one-tap burn buttons, client detail with pack history and full session log, pack catalogue editor (sizes and prices), payments list synced from Stripe webhooks, settings, billing.

Implementation details: burns are append-only ledger entries with an undo window of 10 minutes rather than a delete, so the history stays trustworthy. Support comp sessions as zero-value ledger entries so freebies are visible, not invisible.

Pricing: 15 USD/month via Stripe Checkout, 30-day trial, unlimited clients; client payments go to the trainer's connected Stripe account.