Some work outgrows the spreadsheet it started in: too many files, too many copies, too many handoffs done by hand. A custom application can take its place, built around the process behind the sheet.
What replaces it.
Shared records. One common place for the information, instead of copies.
Access and responsibilities. Clear rules for who can view, update and approve.
A connected workflow. The steps that move the work forward, built in rather than passed around.
Keep what the spreadsheet knows.
A long-lived spreadsheet holds real knowledge in its formulas and in the decisions people make around it. Understand those first. Validate the records, the rules and the exceptions. Then introduce the application with its users involved.
Practical check: Before replacing a sheet, list what its formulas calculate and which decisions depend on them. Anything missing from that list will be missed later.
Sometimes the spreadsheet is still right.
Not every sheet needs replacing. If the work is simple and few people share it, a spreadsheet may be the right tool. Assess the fit before building anything.
Show us the process and where it gets difficult, and work out the smallest useful build.
Read more: What Should the First Version of Your Application Do? · Custom Software