If you have read my scuba post you know I spend a lot of my free time underwater, so it was only a matter of time before one of my projects ended up pointed at the dive world. This one I built together with Kellen Wiltshire, and it came out of watching how much paperwork goes into keeping a dive shop’s gear safe and legal to use.

Every cylinder that gets filled needs to be tracked. When was its last hydrostatic test? When was the last visual inspection? Is it O2 clean? What was the start and end pressure on that last nitrox fill? Traditionally all of this lives in paper logbooks and binders, which works right up until you actually need to find something. So I built a web app to keep track of it all in one place.

Fill Station manages the things a fill operator actually cares about:

  • Gas fill tracking – record air, nitrox, and trimix fills with start and end pressures
  • Visual inspections – a full PSI inspection workflow with per-section grading
  • Cylinder management – hydro dates, visual dates, O2 clean status, manufacturer, and service pressure all tracked per tank
  • Customer accounts – manage clients, their certifications, and the cylinders they own
  • Compressor maintenance – log oil changes, filter changes, air tests, and service hours
  • Email reminders – automated notifications when a hydro test or visual inspection is coming due

Because not everyone walking into a shop should be able to do everything, there are proper roles baked in – regular users, fillers, inspectors, and admins – with permissions enforced at the route level. Login is handled through OIDC (I run Authelia) and Google OAuth via NextAuth, so there are no passwords for the app itself to manage.

Under the hood it is built with Next.js 16 and React 19, TypeScript, Redux Toolkit and React Query on the frontend, and Sequelize talking to a MariaDB database. The whole thing runs from a single docker compose up that spins up the database, a mail server for testing, and the app itself, running migrations and seeding on first boot.

You can see it running live at dive.marshallasch.ca, and the code is open source over on GitHub if you want to take a look.