Product · live
BStrong
A single training log for strength and cardio, built to survive spotty gym wifi.
Problem
Lifters and coaches needed one place to log strength and cardio training that survives an actual gym: a spreadsheet or generic fitness app doesn't handle a dead signal mid-set, and a coach training multiple clients had no shared view of progress without a separate spreadsheet or app.
Approach
A TanStack Start PWA on AWS Lambda and DynamoDB (single-table design), deployed via SST, with an offline-first write queue so a strength set logged with no signal still saves and syncs once the device reconnects.
Outcome
Live in production at bstrong.app for real strength and cardio training.
Under the hood
Every strength set write goes through a durable, IndexedDB-backed queue in the browser: a set logged with no connection persists locally and flushes automatically — with exponential backoff, and idempotently on retry — once the device reconnects. The same service worker that makes this possible also satisfies the install criteria for adding BStrong to the home screen on iOS and Android.
Cardio and interval sessions run through the same logging and sync path as strength sets, so weekly stats, a training-frequency heatmap, and session history (list or calendar) cover both without a second system.
Coaches apply through the app and manage their client roster from the same account they train with — no separate spreadsheet or tool.
Role
- Full-stack development
- Product design
- Infrastructure (AWS, SST)
Stack
- TanStack Start
- React
- DynamoDB
- AWS Lambda
- SST
- better-auth
- Stripe
