Your company runs on a spreadsheet. I turn it into software.

A precision machine shop quoted every job from one Excel workbook with macros underneath. It had been growing for years: a sheet added whenever a question came up, a column added whenever a customer asked something new. It decided the price of everything that left the building, and one person could safely open it.

• Two live price lists. Materials and MaterialsNew both open, both in use. Quotes were being written from whichever one the person happened to click, and only one of them was current.
• Eight duplicate sheets, kept in step by hand. A full parallel set ending in Demo. Every price change had to be made twice, from memory, by the same person — and there was no way to tell whether it had been.
• A formula reaching row 9,872, column seventy-five. Nobody could see the whole of it, so nobody checked it. When a reference below it broke, the workbook did not stop: it returned a number that was simply wrong.
• A #REF! sitting in the material cost column. Not an alarm — just a cell, in a sheet nobody scrolls to, feeding a total somebody quoted from.
• Foglio1, the default name, never changed. Nobody remembered what was on it and nobody dared delete it, so it stayed, and it was still being recalculated.
• Macros written in 2024 that nobody had opened since, and that nobody still at the company could read.

The workbook was not going to fail loudly one morning. It was going to keep producing prices that looked exactly like the right ones.

Fourteen stages, in the order the shop needed them rather than the order that was easiest to build. The costing engine first, with the arithmetic pulled out into small pieces that can each be tested on their own — which is why there are 861 automatic checks and not forty. Then price lists and machine records, customers, quote documents, cost drift over time, estimate against actual, and last the job sheets that go out to the floor.

• One price list, with history. The duplicate sheets are gone. A price change happens once, and the old value is not overwritten — it is kept with the date it stopped applying.
• Prices carry a date, so old quotes still explain themselves. A quote written in March can be reconstructed in November, and a price increase goes out with a letter that shows the customer the arithmetic.
• A quote starts from the drawing. The title block is read out of the PDF and the stock bar out of the STEP file, instead of two people retyping both and one of them mistyping.
• The shop floor got a screen of its own, written separately from the office one. Different hands, different light, a different question being asked.
• Nothing fails silently. Where the workbook returned a plausible wrong number, the software refuses and says which input is missing.
• Several sites on one system, each seeing only its own numbers.

Sheets to keep in step

21 → 1

Unchecked formulas

1,376 → 0

Automatic checks

861

People who can safely change it

1 → all

The point was never the app. It was that the shop stopped having one person it could not afford to lose.

How it actually looks

Real screens, running on the demonstration workshop: nobody’s data is in there.

No spreadsheet here. The file was a notebook and the process was the evening: measurements written on a page during the day, turned into a quote at nine at night, sent two days later. In a trade where the job usually goes to whoever answered first, two days is the whole problem.

• The price list was two years old and lived somewhere else. Materials had moved since; the margin was whatever it had been in 2023, applied to 2026 costs.
• The delay cost the jobs, not the price. Quotes that arrive third arrive after a decision has been made, however good they are.
• Nothing was written down twice. A quote existed once, on paper, in a van. Nobody could tell you what had been quoted to whom, or at what margin, six months later.
• The unpaid hours were invisible. Forty minutes an evening is two hundred hours a year that nobody counts and nobody bills.

Built the whole thing around the only moment that was actually free: the walk back to the van. You describe the job out loud, the software applies your own price list and produces the finished document. Subscriptions, quotas and rate limits were in it from the first week, because a product that cannot charge is a demo.

• Your price list, not a generic one — loaded once, then applied every time, so the margin stops being a memory.
• Every quote is kept and searchable, with what was offered and at what margin.
• The running cost of each quote is shown against the subscription price on a live dashboard. A supplier doubling its rates should appear on a screen, not in an invoice at the end of the quarter.

Time per quote

40 min → 30 sec

Reaches the customer

2 days → same visit

Automatic checks

502

Independent modules

39

How it actually looks

Real pages from the product. I do not publish the screens inside: they would hold somebody’s quotes.

The finished quote is not here. The real ones are customers’ work and I do not publish them, and an invented one would say nothing beyond what you can already read above. If you want to see a real one, we look at it together in twenty minutes.

Invoices issued and paid, rent, bank accounts, money moving between two owners, and the periodic reports — one workbook that had grown a new sheet every time a question came up, and then a second copy of that sheet when the first one got messy.

• A #VALUE! in the middle of a running balance. Every row below it inherited the error, so a figure the owners looked at monthly had quietly stopped being a number.
• Two summary sheets, both maintained. When they disagreed, whichever one was open won.
• Formulas across whole columns ($B:$B), so one paste in the wrong place silently changed totals elsewhere.
• No access control at all. Anyone who could open the file could change a paid invoice back to unpaid, and nothing recorded that they had.

For an office that had never used anything but Excel, the design decision that mattered most was not a feature: it was that the program starts with a double click and needs no internet. Data in one file, kept on their own machine, with a backup they can copy.

• The whole history was imported from the old workbook. Nobody had to retype a year of invoices before the thing was useful.
• Two logins: one that can change everything, one read-only for whoever just needs to look.
• One number, computed once. Where there were two summary sheets, there is now a single figure and no argument about which is right.

Sheets

20 → 1 program

Conflicting summaries

2 → 0

History retyped

none

Starts with

1 click

I publish no screenshots of this one. It runs on a real company’s accounts and there is no version of it with invented data, so there is nothing I could show you without showing you their figures. If you are wondering what I would do with yours, that is the answer.