What Does Locking an Excel File Mean?

Locking an Excel file means applying password-based encryption so that the spreadsheet cannot be opened, viewed or edited without authorization. Once encrypted, Excel will always ask for a password before granting access.

Difference Between Sheet Protection and File Encryption

Sheet protection only restricts editing but allows viewing of data. File-level encryption completely blocks access until the correct password is entered, making it the strongest security method.

Why Excel Password Protection Is Important

Protect salary sheets
Secure GST and tax reports
Prevent data leaks
Protect client databases
Ensure compliance

Military-Grade Encryption Explained

Excel uses AES-based encryption standards. When a password is applied, the file contents are mathematically scrambled and cannot be recovered without the correct key.

Works Across All Excel Versions

Password-protected XLSX files generated by this tool open normally in Microsoft Excel, Google Sheets, LibreOffice and mobile Excel apps.

Common Use Cases

Sending files via email
WhatsApp document sharing
Office data storage
Cloud backups
Legal documentation

Client-Side Encryption Technology

All encryption occurs inside your browser memory. Your Excel file and password are never uploaded to any server, ensuring maximum privacy.

Password Safety Warning

If you forget the password, the file cannot be recovered by anyone — including GKPTool. Always store your password safely.

Frequently Asked Questions

Is Excel file locker free?
Yes, unlimited usage is completely free.

Are files uploaded?
No. All encryption runs locally.

Can passwords be recovered?
No. Encryption is irreversible without the password.

Does it support XLS files?
Only XLSX format is supported.

Lock Excel File Online – Password Protect XLSX