Replace a spreadsheet that broke under load
Turn the 47-tab spreadsheet everyone's afraid to touch into something that won't melt next quarter.
What you'll have at the end
A real app with the same data, the same logic, and the same people using it — except now two people can edit it at once, history is automatic, and you don't need to remember which tab has the 'real' numbers.
01
Who this is for
- Teams whose 'source of truth' is a Google Sheet older than the company
- Anyone who has typed the words 'don't touch the pivot tab'
- Builders who already shipped one tiny app and are ready for something with real data
02
How to frame the idea
The spreadsheet is the spec. Don't redesign — replicate. Get the same columns, same filters, same sort order live first, then start adding the things the sheet couldn't do: real permissions, edit history, validation that doesn't depend on conditional formatting.
03
What people actually build
Client tracker → client CRM
The sheet has 12 clients and 30 columns. Move it to a real app with proper records, statuses, and a notes timeline.
Project board → milestone tracker
Replace the 'project status' tab everyone copies. Now Mondays don't start with 'who updated this?'
Asset registry → equipment app
Devices, warranties, who has what. The sheet broke at 200 rows; the app handles 5,000.
04
Tool choices, honestly
Lovable + Lovable Cloud
You want UI + database + auth in one go without standing up infrastructure.
Supabase direct
You're comfortable with SQL and want to design the schema before you describe the UI.
Retool / Glide
You'd rather point at the existing sheet and skin a UI on top while you decide whether to fully migrate.
05
Prompts you can lift
Schema-first
Here are my spreadsheet columns: <paste headers + 3 sample rows>. Design a normalized database schema. Tell me which sheet columns become tables vs columns, where the foreign keys go, and what validation rules I should enforce. Don't write any UI yet.
Migrate the data
Generate a CSV import script that takes my sheet (column mapping: <mapping>) and inserts into the tables you just designed. Skip empty rows. Log anything that doesn't validate so I can review.
Lock multi-user safety
Two people might edit the same record at the same time. Add optimistic UI with a clear 'someone else updated this — refresh' message. Don't let one person silently overwrite the other.
Save and reuse these prompts in PromptlyDo™ with your favorite AI.
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- Right-click any prompt above and save it to PromptlyDo™
06
What tends to break
- Rebuilding the spreadsheet pixel-for-pixel including the broken bits. Take the chance to drop columns nobody filled in.
- Forgetting history. The sheet was bad but at least it had version history. New app should too.
- Bulk imports that silently swallow bad data. You'll find out three months later when a report is off.
- No backup of the original sheet before you cut over. Always keep the sheet read-only for 90 days.
07
What AI forgot to ask you
- Who's allowed to edit vs view? The sheet had no answer — the app needs one.
- What's the unique key for each row? Names are not unique. Emails change.
- What happens to the formulas that referenced this sheet from elsewhere?
- Which 'inferred' columns (the ones with a formula) are now derived in the app, and which are stored?
08
Before real users see it
- Data migrated, row counts match, spot-checks pass.
- Two people editing different records at the same time both succeed.
- Two people editing the same record see a conflict warning.
- I can export back to CSV in 10 seconds if I need to.
- The original sheet is locked read-only with a 'use the app' banner.
09
Questions to sit with
- 1.Which spreadsheet behaviors am I keeping, which am I dropping, and which am I improving?
- 2.Who owns this app once it's live — and do they have edit access to the schema?
- 3.If the app went down for 4 hours, what would the team do? If the answer is 'panic,' you need a fallback.
Ready to app it?
Take this path into your tool of choice — and when you finish (or get stuck), share what you learned so the next builder doesn't reinvent it.