How to convert a Google Sheet into an app

Working out which route your sheet needs

1. 1

   Write down who opens it

   Not roles in the abstract, the actual people. Most sheets that have become a problem have between five and thirty readers, and the trouble started at a specific number.

2. 2

   Ask whether they may all see everything

   This is the whole decision. A shared sheet has one permission for the whole file, so anyone who can read a row can read every row. If that is fine, you need a better interface. If it is not, you need a different storage model.

3. 3

   Check the sheet is not already the bug

   Two people editing the same cell, a filter that changed everyone's view, a formula somebody dragged over a column. If these are your complaints, the interface is not the problem and a wrapper will not help.

4. 4

   Pick from the answer, not from the demo

   Everyone may see everything: an app builder over the existing sheet is the fastest good answer. They may not: move the data into something with per-person rows before building anything on top.

5. 5

   Move the data once, deliberately

   Export as CSV while the sheet is still the source of truth, and keep it. Whatever you build, having the original export means a bad migration costs an afternoon rather than the records.

What actually goes wrong with the spreadsheet

Worth naming precisely, because the right route depends on which of these you have, and two of them are not solved by turning the sheet into an app.

• Everyone can see everything. Sharing is per file. Once somebody can read the sheet they can read every row in it, and hidden columns and protected ranges are presentation rather than security.
• Nobody knows who wrote a row. People type their own names, so you get three spellings of the same person and no way to tell who actually entered something.
• Someone breaks it. A drag of a formula, a sort that moves half the rows, a filter that changes what everyone else sees.
• It is not a size problem. Google's own limit is generous, and quoting it here is fair rather than convenient:

Up to 10 million cells or 18,278 columns (column ZZZ) for spreadsheets that are created in or converted to Google Sheets.

Files you can store in Google Drive, Google Drive Help

Almost nobody converting a sheet is anywhere near ten million cells. If someone tells you a spreadsheet cannot hold your data, they are usually selling something. The reasons to convert are the first three, and they are all about people rather than volume.

The three routes

The row that decides most cases is the third one. An app builder pointed at a spreadsheet gives you a much better interface onto the same permission model. The data is still one file that anyone with access can open, and for a sheet holding pay, grades, addresses or anything personal, that is the problem you were trying to solve.

The trap in keeping the spreadsheet as the database

This is the single most expensive mistake in this whole exercise, and it is easy to make because the demo looks right.

You build a lovely interface where each person sees only their own records. It works. But the underlying sheet still contains everyone's records, and the filtering happens in the app rather than in the storage. Anyone who can reach the file directly, and by definition the app's own account can, sees all of it.

For a rota, a signup sheet or a book club list, that is completely fine and you should not overthink it. For anything with money, health, grades, addresses or performance in it, an interface that hides rows is not the same as storage that does not return them, and the difference tends to be discovered by somebody who was not supposed to find it.

Having an agent build it instead

The newest route, and the one that changes what the work is rather than how long it takes. Instead of learning a builder or writing an app, you describe the thing to an AI agent you already use, and it creates a real app: its own URL, sign-in by emailed link, a database where each row records who created it, and permissions per collection rather than per file.

Homespun is where the same agent that built the thing can host it. People sign in with their email, so the app can tell who is who and every row remembers who created it; permissions are set per collection, so some people can approve and others can only submit; and the agent keeps read and write access to the collections it is allowed, so it can keep working on the data instead of handing you a page and walking away. It is free today, and there is no paid plan to buy.

The part that matters after launch is that the agent keeps access. A converted spreadsheet is never finished: somebody always needs one more column, one more view, one more rule about who may edit what. On the other routes each of those is an editing session or a deploy. Here it is a sentence, because the agent still holds read and write access to the app's data.

Being straight about the cost of this route: your data moves out of the spreadsheet, you get a subdomain rather than your own domain, there is no offline mobile app, and the product is young. If any of those is disqualifying, one of the first two routes is your answer.

When to keep the spreadsheet and convert nothing

Said plainly because most pages answering this query will not say it, and it is the right answer more often than they suggest.

• Everyone genuinely may see everything. A team roster, a shared reading list, a public tally. A spreadsheet is excellent at this and free.
• It is mostly a calculation. Formulas, pivots, charts. No app is going to beat a spreadsheet at being a spreadsheet, and converting one usually means losing the analysis.
• Two or three people use it. Below about five, the coordination problem is not real yet and the conversion costs more than the confusion.
• It is temporary. One event, one season, one project. Building an app for something that ends in six weeks is a hobby, not a solution.

Questions people ask next

Primary sources

Every claim about Claude on this page comes from Anthropic's own documentation, quoted rather than summarised so you can check it yourself.

• Files you can store in Google Drive, Google Drive Help
• Pricing, Google AppSheet
• Model Context Protocol documentation