Discover how to password protect an Excel file using the .NET REST API in this step‑by‑step guide. We’ll walk you through building a .NET Cloud API application that encrypts Excel workbooks, following clear, concise instructions. The resulting solution runs on any .NET‑compatible platform—macOS, Linux, or Windows—and the conversion is completely free.

Prerequisite

• Create an account and get API credentials to password protect an XLS
• Download Aspose.Cells Cloud SDK for .NET to encrypt an XLS with password
• Setup C# .NET project with the above SDK to set password for the XLS file

Steps to Encrypt Excel File using NET Low Code API

1. Configure the Client ID and Client Secret for the API to encrypt the Workbook with a password using NET REST API
2. Instantiate the CellsApi class with client credentials to perform password protection of an XLS file
3. Specify the source XLS file names and load the source XLS using a name and File object in a HashMap
4. Instantiate the ProtectWorkbookRequest to set the password and other properties
5. Create an instance of the PostProtectRequest to set the map files and ProtectWorkbookRequest instance
6. Call the PostProtect request method to encrypt Excel file using NET low code API
7. Save the password protected Excel file/s on the local disk

The above steps manage to password protect Excel using NET REST API. We will commence the process with the configuration of the SDK and creating the CellsAPI class instance. We will then open the source XLS files using a HashMap and instantiate the ProtectWorkbookRequest and PostProtectRequest classes that are further used for setting the password protection for the Excel files using the PostProtect() method.

Code for Password Protect Excel using NET REST API

With just a few lines of code, you can password‑protect an Excel workbook using the .NET low‑code API. Provide the source Excel files, a password, and any optional properties you need. After building the request message, calling PostProtect() secures the workbook and returns the password‑protected Excel files, ready to be saved to disk or stored in a database.

In this article we demonstrated how to encrypt a workbook with a password using the .NET REST API. If you’re interested in converting Excel files to PNG, be sure to read our guide on how to Convert Excel to PNG with NET REST API.