The spreadsheet nobody understands any more, turned into one that does.
It started as a simple sheet three years ago. Today it has twelve tabs, macros nobody dares touch, and exactly one person who really knows how it works — and if that person goes on holiday, the process stops. It’s not a spreadsheet problem: it’s an important process that never had the budget to become a real tool, until the cost of not having one became obvious.
How I approach it
I review the file exactly as it is — with its patches and exceptions, not the idealised version someone would describe from memory — because that’s where the real knowledge of the process lives, however badly organised. I build a tool with its own interface that does the same thing without the fragile formulas: with permissions, a change history, and no dependency on one person knowing where the trick is.
What usually fits
A custom internal application, with a real database instead of a file living on a laptop, and an interface designed for whoever uses it every day — not for whoever built it. Migration of existing data included: nothing gets lost in the switch.