Shared Sheet Guardrails

Let people edit your Google Sheet™ without breaking it. Lock the formulas, add the dropdowns, and see what's been broken — in two minutes. Your collaborators don't install anything.

Install free See it in 60 seconds

Install: from the Google Workspace Marketplace™ listing, or in Google Sheets™ choose Extensions › Add-ons › Get add-ons and search for “Shared Sheet Guardrails”. Questions: support@appgarden.co.uk.

See it in 60 seconds

A messy shared tracker → Check → Set up (roles proposed, confirmed) → Apply → a collaborator's account: the locked formula warns, the dropdown refuses a typo → back to the keeper: Check shows what still got through → Fix.

Six ways a shared sheet breaks

A total typed over. Someone types 180 over =D42*E42. It never updates again.
A paste past the dropdown. Pasting skips data validation, so “done”, “Done ” and “Completed” all get in.
One column sorted alone. Names end up next to someone else's hours.
A filter left on for everyone. Half the rows vanish for the whole team.
A range that stops at row 50. SUM(F2:F50) quietly misses every row added since.
A blocked ARRAYFORMULA. One typed cell in its path and the whole column shows #REF!.

Nobody else installs anything

The guardrails are Google Sheets™' own features: protected ranges, dropdowns and data validation, red highlights, a frozen header and notes on each header. So they work for every collaborator, on every device — including the Sheets app on a phone — without anyone else installing a thing. The add-on is the keeper's tool for setting them up, checking them, and taking them off again.

How it works

Check this sheet — free, unlimited. Every finding names its cells, with “Show me” and how to fix it by hand.
Set up — the add-on reads the sheet and proposes a role for each column (formula, dropdown, date, ID…) with its reason. You confirm, preview, apply.
Check again any time. The check compares the sheet with the rules you saved, so a renamed header or a column sorted on its own shows up too.

Who it's for

Teams and offices with a shared tracker or rota · school staff (cover rotas, trip lists, room bookings) · clubs and charities (volunteer rotas, sign-up sheets) · small businesses (stock, jobs, quotes). Anyone who “keeps” a sheet the whole team edits.

Free and Pro

Free — £0	Unlimited Check this sheet (every finding, click-to-cell, the protection audit, how to fix by hand) · Quick protect (formulas and headers, warning only) · Undo last setup · Remove guardrails · checking against a contract someone else saved.
Pro — £4/month or £29/year	The full Set up wizard (locks, dropdowns, highlights, notes, a Sheet rules tab) · one-click fixes · Check all tabs · contracts (save, refresh, export, import, apply to similar tabs) · report tab and CSV · 3 Google accounts · 30-day full refund.

Only the keeper pays. Collaborators never need the add-on. Schools, PTAs, clubs and registered charities: 50% off. If a subscription ends, the guardrails already on your sheets stay on and keep working.

See prices

Your data

Nothing in your spreadsheet leaves Google. The add-on asks for two permissions only: this spreadsheet only (spreadsheets.currentonly) and show a sidebar (script.container.ui). The only thing it ever sends anywhere is a licence key and an anonymous install id. Privacy notice.

Questions

Do collaborators need the add-on?: No. They see Sheets' own lock warnings, dropdowns and highlights.
Can the owner still edit?: Yes, always. Google does not let anyone lock the file's owner out.
Is this security?: No — guardrails. Anyone with edit access can still make a copy, and viewers are unaffected. It stops accidents, not people.
How do I take it all off?: Contract → Remove guardrails. One click, free, in any licence state. Every guardrail it added goes and what was there before comes back. Report tabs and any Moved by guardrails tab (your own data) stay until you delete them.
Does it work on phones?: The guardrails do. The add-on itself runs in Sheets on a computer.
What about Sheets Tables?: If your data is in a Table, use the Table's own column types; the check still reports what was broken.
My admin blocks add-ons.: Ask them to allow it from the Google Workspace™ Marketplace; it asks for the current spreadsheet only.
Does it check link sharing?: No — that needs Drive access this add-on deliberately doesn't ask for. See Personal Data and Sharing Check.
Is it made by Google?: No. AppGarden is not affiliated with Google.

From the same garden

Hardcoded Value Detector — numbers typed over formulas, in Excel. Personal Data and Sharing Check — personal data before you share a sheet.