How do I turn a spreadsheet process into an app?

Start by writing down what the spreadsheet really does: who opens it and why, the rules hidden in its formulas, colors and comments, and the steps that happen outside it, by email or phone. Then specify the app from that understanding, not from the layout of the sheet.

A spreadsheet that runs part of a business is usually doing more than it appears to. Much of the process lives in the heads of the people who use it.

What should I look for in the spreadsheet?

• Formulas: each one is a business rule. A discount, a due date, a reorder point.
• Colors and flags: red often means "needs attention," but who decides, and what happens next?
• Comments and notes: frequently the exceptions.
• Tabs and copies: a tab per month or a copy per person usually means a record the app should keep properly.
• Columns nobody uses: ask before you drop them; someone may rely on them once a year.

What happens outside the spreadsheet?

Ask each person who uses it to walk through a real case from start to finish. Where do they get the information? Who do they email? What do they do when something doesn't fit? Those steps are part of the process even though the sheet never shows them.

Who should I ask?

Everyone who touches it, separately. The person who built the sheet knows the formulas; the people who use it every day know the workarounds; the manager knows what reports come out of it. Their answers often differ, and the differences need a decision.

What does the app need that the spreadsheet didn't have?

• Roles and permissions: who may see and change what, instead of everyone editing everything.
• A history: who changed a record, and when.
• Rules applied consistently, not dependent on someone remembering.
• Connections to the systems the spreadsheet was copied into or out of.

Should the app look like the spreadsheet?

Not necessarily. People may want a familiar view, but the app should be designed around the work, not the grid. Specify what the software must do and let the builder design the screens.

How do I know I've captured everything?

Write each requirement as a testable statement, add acceptance criteria, and have the people who use the sheet confirm them. Then compare a month of real spreadsheet data against the rules you wrote and look for cases they don't cover.

Mochlion gathers this from the people who use the sheet and turns it into a Build Specification; see the sample for what one looks like.