Case study: Our own product · iOS fitness app
Gymnal
- Product Strategy
- UX/UI Design
- iOS App Development
- AI-Assisted Development
- On-Device AI
- Subscription Monetization
- Website
- Branding
- Ad Creative & Social Marketing
The Idea
Gymnal started with one idea: lifters and runners should get their own data back. Every session, set and rep stays on the phone, and the intelligence runs locally too.
What We Built
A private training journal for iPhone with fast logging, structured programs, progress tracking, Apple Health import and on-device Training Intelligence. Free to use, with optional Pro and Max tiers.
How We Built It
Jackall Creative owns and created Gymnal. Jared handled product strategy, UX/UI design, iOS development with AI-assisted tooling, subscriptions, the website, branding, ad creative and social marketing in-house.
Where It Stands
Gymnal launched on the App Store on August 12, 2026 and has been updated through version 1.0.8 (September 30, 2026). It’s a live product that we build, run and market ourselves.
Why It Matters
The skills behind Gymnal are the ones we bring to clients: product thinking, web and app development, practical AI and marketing that ships.
What Jackall did
Designed, built and marketed in-house.
- 01
Product strategy
Defined Gymnal as a private training journal: on-device data, no Gymnal account, free logging with optional upgrades.
- 02
UX/UI design
Designed the full iPhone experience, from fast set logging and programs to charts, insights and settings.
- 03
iOS app development
Built the app with React Native and Expo, a local SQLite database and read-only Apple Health import.
- 04
AI-assisted development
Used AI coding tools throughout the build, the same hands-on AI workflow we teach clients.
- 05
On-device AI
Built Gymnal Training Intelligence: recaps, scoring and Ask Gymnal answers calculated on the phone, not in a cloud AI service.
- 06
Subscription monetization
Free Gymnal Lite plus Pro and Max subscriptions through Apple, with RevenueCat for purchases and restores.
- 07
Website
Designed and launched gymnal.app with features, a full User Guide, privacy, support and terms pages.
- 08
Branding & marketing
Created the red G mark and wordmark, App Store assets, ad creative and social content.
Inside the app
Real screens from Gymnal.
-
Home hub -
Live workout logging -
Paste to log -
Progress & PRs -
Training Intelligence -
Structured programs -
Apple Health import -
Privacy & data
Features
What Gymnal does.
Log workouts fast
Open an exercise and see last time’s weight, reps and rest. Live sets, rest timing and session progress in one flow.
Paste to log
Paste a workout from notes or shorthand. On-device Training Intelligence builds a reviewable log before anything is saved.
PRs & progress
Estimated 1RM updates with every working set. Weight, rep, e1RM and volume PRs are flagged as they happen.
Structured programs
12 built-in programs across strength, hypertrophy, conditioning, mobility and running, from High30 to a 126-day Marathon plan.
Training Intelligence
On-device recaps of the last week, month and full history, plus a 0–100 quality score for every workout.
Apple Health import
Apple Watch runs, treadmill, rower and bike sessions import from Apple Health with deduplication. Read-only.
Private by design
No Gymnal account and no Gymnal cloud. Portable on-device backups and user-controlled export.
Free, no ads
Unlimited workout logging on Gymnal Lite. Optional Pro and Max add programs, deeper analysis and export.
The tech
How it’s built.
- App
- React Native and Expo (SDK 54), built and shipped with EAS.
- Data
- Local SQLite on the device. No user-account server and no Gymnal cloud.
- Health
- Apple HealthKit, read-only, for workouts, runs, sleep and body metrics.
- AI
- A rule engine plus an on-device language model (a one-time ~1.1 GB download), with Apple on-device speech for Ask Gymnal.
- Payments
- Apple in-app subscriptions with RevenueCat.
- Web & delivery
- gymnal.app and the model download are delivered through Cloudflare; app updates through Expo.