Warehouse opening hours instead of Excel — how a small app replaced a shadow process

When is which warehouse open, when closed, when do special hours apply? Many parties in a logistics operation need this information: operational teams, planning, neighbouring systems.

The hours were maintained in Excel sheets. What began as a pragmatic solution became more error-prone with every location: files were passed around, it was unclear which version was current — and who was allowed to make changes was not technically enforced anywhere.

A classic shadow process: business-relevant data in a spreadsheet that was never meant for it.

A compact web app replaced the sheets: a backend with REST APIs as the reliable source for all systems that need the hours, and a UI where the hours are maintained directly per location.

For the transition there was a CSV import — existing spreadsheets could be taken over directly instead of re-entering everything.

Not everyone may change the hours of every location. The app was built accordingly from the start: authentication via OAuth2, fine-grained authorization with Open Policy Agent (OPA). Who can see and maintain which locations is defined as policy — not hidden in code branches.

In the Excel world, this control simply did not exist: whoever had the file could change everything.

This pattern exists everywhere: a spreadsheet that was only meant to bridge a process "for now" becomes critical infrastructure — without access control, without history, without interfaces.

Replacing it does not have to be a major project. A small, focused app with clean interfaces and built-in security is often enough — what matters is understanding the process before building.