If you have sensitive data you'd like to keep from prying eyes in a Microsoft Excel file, the easiest way to protect it is with Excel's built-in password tools.

Learn how to unprotect Excel sheets or workbooks without a password using this simple step-by-step guide. No software required!

You can add or remove a password from your Excel spreadsheets through the File tab. You'll do it slightly differently on a Mac and PC.

Sending Excel files containing crucial financial and business data has risks. To add a layer of protection, you should learn to password protect an Excel file.

Whether you’ve forgotten the password or received a protected file from someone else, unlocking an Excel spreadsheet without the password may seem like an insurmountable challenge.

There are several options available to you to protect your Excel file with a password. Remember that once you protect the Excel file, you cannot open it without entering the password.

How to Recover an Excel Password in OS X. The Mac operating system provides a way for you to lock Excel with a password to prevent unauthorized use by using Keychain Access.

At the file level, you can password protect an Excel workbook in two ways: You can determine who can get in and who can save changes.

I just performed a preliminary Google for "crack excel password" and a bunch of sites came up. I've used Squrf's method to get around Word passwords before, but I've never tried a spreadsheet.