Case Study · Mobile App + Platform

GridGrind

A sports performance and recruiting platform, built end to end and submitted to the App Store: athletes film position-specific challenges, certified coaches grade them, and every grade builds a verified, ranked profile recruiters can trust. It is also a full online business for coaches and trainers, who run paid services and get paid on the platform. Web at gridgrind.app.

RoleFounder: design, build, brand, go-to-market

StackReact Native · Supabase · Stripe · AI video + voice

ExtrasCoach marketplace · Payments & payouts · XP engine · Referral system · AI avatars

Challenges: coaches post position drills with intro and demo film

Verified profiles. XP, skill ratings, and coach reviews build a ranked record

Film grading: submissions scored by multiple certified coaches, monetized reviews

The Business Engine

Not just an app. An economy.

The hard part was not the screens. It was the money. I built a multi-sided marketplace where coaches and trainers run a real online business, and every payment and payout is wired end to end through Stripe.

Coaches & Trainers Run their own storefront and get paid for:

Paid film-review voice notes
Game-film breakdowns they price themselves
1-on-1 training sessions
Video training modules
Referral commissions for bringing on other coaches

Tiered plans: Trainer $24.99 · Team Coach $34.99 · Premium Coach $49.99 (AI avatar + recruiting visibility)

Athletes Turn their grind into income:

Sell highlight reels
Collect tips from parents and fans
Earn on referrals

Fans & Parents Fuel the ecosystem:

Subscribe for premium access
Tip and support athletes
Earn referral commissions

Guardrails built into the code: role-locked commissions and NCAA-safe rules, so a coach can never earn off an athlete. The kind of compliance logic most builds skip and most platforms get sued over.

Under the Hood

The engineering most apps skip.

Un-gameable XP engineScores computed by database triggers: the average of the first 10 certified coach grades, then the score locks. A player's own team coaches are excluded from the math, so nobody inflates their kid.

Smart grader assignmentSubmissions are soft-random routed to certified coaches of that position, never the athlete's own team. Multiple opinions, no bias.

Live 1-on-1 video trainingServer-provisioned video rooms for paid coaching sessions, booked and billed inside the app.

AI coach avatars and voicesPremium coaches get an AI avatar and cloned voice that produce training content for them. Their expertise, scaled without their hours.

Full team suiteRosters, group chat with parents auto-included for minors, practice and event scheduling, team leaderboards, and private challenges for the roster only.

Social layerFeed with highlights, post bumping, profile-view notifications, messaging and group chat, and an Explore tab for every role.

Minor-safe by designCOPPA parental consent gate, age verification, and adults-only rules on tipping, enforced in code, not in a terms page nobody reads.

Compliance-grade payoutsRole-locked referral commissions and NCAA-safe earning rules. A coach can never profit from an athlete, structurally.

Web-to-app paymentsStripe checkout on the website unlocks subscriptions in the app via webhooks, with reconciliation for people who pay before they sign up.

Ships like a product companyOver-the-air updates, product analytics on every key event, custom notification sounds, an in-app challenge approval workflow, and a support ticket system.

The marketing engineLanding site, founding-coach funnel with live scarcity counter, Stripe subscriptions, and an AI-produced content pipeline. Reels, carousels, and a fully AI-generated commercial.

AI-generated brand campaignThis athlete does not exist. Campaign visuals, video, and voiceover produced with an AI pipeline I run in-house. The same firepower your brand gets.

If I can build this solo, imagine your project.

Apps, platforms, AI systems: scoped honestly on one call.

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