Blue Moon 5 Miler

The problem

The Blue Moon 5 Miler is a local road race. Most small races run on off-the-shelf registration platforms that take a meaningful cut of every signup and offer a registration experience that feels like 2009 — clunky forms, jarring payment redirects, no real control over the event site.

I wanted to see if I could build the whole stack myself for a single race, keep the runner experience tight, and learn a lot about payment infrastructure along the way.

What I built

• Public race site. Fast, responsive event page with course info, results archive, and a registration CTA that doesn't get in the way.
• Registration flow. Form validation, participant data capture, emergency contact, t-shirt sizing, confirmation flow.
• Stripe payments. Checkout sessions, webhook verification, refunds, and dedupe for the inevitable double-submits.
• Supabase backend. Postgres tables for participants with row-level security, real-time subscriptions for the admin dashboard.
• Admin view. Live registrations list, CSV export, manual refund hooks, ad-hoc updates.

Technical highlights

Stripe webhook verification — done right the second time

The first version trusted the Stripe redirect to confirm payment. Bad idea — a runner with a flaky connection had their card charged but their registration never recorded. I rebuilt the flow around webhook verification with idempotency keys, and the failure mode disappeared.

Supabase row-level security

Participant data sits in Postgres with RLS policies that constrain reads and writes to the right contexts. The admin dashboard subscribes to real-time changes so I can watch signups roll in on race week without refreshing.

End-to-end ownership

DNS, deploy pipeline, schema design, UI, copy, transactional emails, refund policy. Owning all of it at once is the part of side projects that doesn't translate to most jobs — every decision compounds, and every shortcut shows up later.

What I'd do differently

I'd start with the admin dashboard instead of finishing it last. The thing I actually use most often during a race is the participant list — and building it last meant I shipped without a proper search field. Future me would have appreciated past me solving that earlier.

Takeaway

Side projects are where I find out what I actually believe about engineering. At work there are good reasons to defer to existing systems; on a side project you have to choose, defend, and live with each one. This one taught me that I'd rather build payment infrastructure carefully than build it cleverly.