QuickMergePassword Protect an Excel File
Lock the sheets in an .xlsx workbook so the cells cannot be changed without your password. The file is opened, modified and saved inside this browser tab — it is never uploaded.
How do I password protect an Excel file?
Drag an .xlsx workbook here
or click to browse — the file is read in this tab and never uploaded
Read this before you rely on it. This applies Excel’s sheet and workbook protection — the feature that stops people editing your cells. It does not encrypt the file, and it is not the “password to open” prompt. Anyone who receives the workbook can still open it and read everything in it. If the contents must be unreadable without a password, see what to use instead.
What this locks, and what it does not
Excel has two entirely separate features that both get called “password protecting a spreadsheet”, and the difference decides whether your data is actually protected. Almost every complaint about Excel passwords traces back to somebody using one when they needed the other.
Sheet and workbook protection — which is what this tool applies — controls editing. The cells are locked, and Excel refuses to change them without the password. Anyone can still open the file and read every number in it. This is the right tool for a budget template you are circulating, a rota, a price list, a form with calculated cells, or any sheet where the risk is somebody overwriting a formula rather than somebody seeing the data.
File encryption — Excel's Encrypt with Password — controls opening. The file's contents are genuinely encrypted with AES, and without the password there is nothing readable inside it at all. That is what you need if the spreadsheet holds salaries, personal data, medical information or anything else that a person seeing it would be the problem.
This page does the first one. It says so above the tool rather than in a footnote, because choosing protection is a security decision and a tool that lets you believe you encrypted a file when you did not has done real harm.
How to protect the sheets
- Drop in the .xlsx file. It is read in this tab; the worksheet count appears once it has been parsed.
- Choose a password. Tick “show the password” if you would rather see what you are typing — worth doing, because there is no confirmation field and no way to recover it later.
- Decide what else to lock. By default the cells are locked but sorting, filtering and formatting still work, which keeps a shared sheet usable. Tick the extra options if the layout itself must not move.
- Protect and download. The workbook saves with
-protectedadded to its name so the original is not overwritten.
Open the result in Excel, LibreOffice or Google Sheets and try to type into a cell: Excel refuses and tells you the sheet is protected. Removing the protection needs Review → Unprotect Sheet and the password.
Locking the workbook structure
Structure protection is the option ticked by default, and it solves a different problem from cell locking. It stops sheets being added, deleted, renamed, moved or unhidden. On a multi-sheet workbook that matters more than people expect — a report where sheet three feeds the summary on sheet one breaks completely if somebody deletes or reorders sheets, and cell protection alone does nothing to prevent that.
It is also what stops a hidden working sheet from being unhidden by a curious recipient. That is worth stating precisely: it prevents the sheet being revealed in Excel's interface. The data is still inside the file. Hiding a sheet is tidiness, not confidentiality.
When you need real encryption instead
If the requirement is that people must not be able to read the spreadsheet, sheet protection is the wrong feature and no amount of it will do the job. Two honest routes:
Use Excel itself. File → Info → Protect Workbook → Encrypt with Password applies AES-256 encryption to the whole file. Excel then asks for the password before it will open the workbook at all. This is the genuine article and it is built into software you already have.
Convert it to a PDF and encrypt that. If the spreadsheet is going out as a read-only report rather than as a working file, exporting to PDF and adding a password with real AES-256 encryption gives you an encrypted document that opens anywhere, and removes the risk of somebody editing figures and forwarding them as yours.
A note on strength, since it explains why this page is careful. Sheet protection stores a 16-bit hash of your password — about 65,000 possible values — and Excel checks against that hash. It was designed to prevent accidental edits, and Microsoft's own documentation describes it as a way to stop people changing data rather than as a security measure. Treat it as a lock on a filing-cabinet drawer: enough to mean “do not edit this”, not enough to protect a secret.
Nothing is uploaded
An .xlsx file is a ZIP archive containing XML. This page opens that archive with JSZip, writes the protection element into each worksheet, and repackages it — all in this browser tab, all against memory on your device. Spreadsheets are where organisations keep payroll, customer lists and financial models, and there is no reason for a file like that to be sent to a stranger's server to have an attribute set on it. There is no upload, no account and no stored copy. Verify it from your browser's network panel if you would rather not take our word for it.
If you have a protected workbook of your own and need the protection off again, the unprotect tool is the other half of this pair. And because the same confusion between locking and encrypting runs through PDFs too, the guide to locking and unlocking documents is worth reading before deciding which protection a file actually needs.
Frequently asked questions
Drop the .xlsx workbook above, choose a password and select Protect and download. Every worksheet is locked against editing and, by default, the workbook structure is locked too. The file is modified inside this browser tab and never uploaded.
No, and the distinction matters. This applies sheet and workbook protection, which stops people editing the cells. Anyone can still open the file and read it. For contents that must be unreadable without a password, use Excel’s own File → Info → Encrypt with Password, which applies AES-256.
Sheet protection controls editing; encryption controls opening. A protected sheet can be read by anyone and changed by no one without the password. An encrypted workbook cannot be opened at all without it. Use protection for templates and shared sheets, encryption for confidential data.
Yes. This writes the standard SpreadsheetML protection element that Excel itself writes, so Excel, LibreOffice Calc and other spreadsheet software honour it. Removing it in Excel is Review → Unprotect Sheet with the password.
Not very, by design. It stores a 16-bit hash of the password — roughly 65,000 possible values — and Microsoft documents the feature as a way to prevent unwanted changes rather than as a security control. It reliably stops accidental edits. It does not protect a secret.
No. This page cannot recover, reveal or bypass an unknown password, and does not attempt to. Note the password down somewhere safe before you protect the file — that advice is the whole of the recovery plan.
It stops sheets being added, deleted, renamed, moved or unhidden. That matters on multi-sheet workbooks, where deleting or reordering a sheet can break formulas on another one — something cell protection alone does nothing to prevent.
No. An .xlsx is a ZIP of XML files; this page opens it with JSZip, writes the protection element into each worksheet and repackages it, entirely inside your browser. Nothing is sent anywhere and no copy is kept.
Not directly. This works on the .xlsx format. Open an older .xls in Excel and save it as .xlsx first. A CSV is plain text with no concept of protection at all — it has to become a workbook before it can be protected.