Watermarks in Excel are a great way to brand documents, mark them as confidential, or protect content from misuse. Whether you want to add watermark in Excel, insert a watermark in Excel sheet, or remove Excel watermark, Aspose.Cells Cloud SDK for .NET provides a seamless and reliable way to manage watermarking operations programmatically.

Why Add a Watermark in Excel?

Adding a watermark in Excel helps communicate document purpose and ownership. Some common use cases include:

  • Marking internal or draft documents as “Confidential” or “Internal Use Only.”
  • Adding branding elements such as logos or company names.
  • Preventing unauthorized distribution or tampering.
  • Making data sheets appear more professional.

Excel Processing API

Our .NET Cloud SDK Aspose.Cells Cloud SDK for .NET is a robust solution providing the capabilities to create, edit and transform Excel workbook to other supported formats. It also offers the features to apply watermark in Excel, create watermark designs, or remove existing Excel watermarks without needing Microsoft Excel installed.

Before adding or removing a watermark, install the SDK via NuGet and obtain credentials from the Aspose Cloud Dashboard.

PM> NuGet\Install-Package Aspose.Cells-Cloud -Version 25.9.0

Key Features

  • Add watermark to Excel worksheet from image or text.
  • Remove watermark in Excel when not needed.
  • Apply consistent watermarks across multiple worksheets.
  • Automate watermarking using REST or cURL commands.

Add Image Watermark in Excel in C#

This section provides the details on how we can programmatically insert watermark in Excel using C#.

Step 1 - Create an instance of CellsApi.

CellsApi cellsApi = new CellsApi(clientID, clientSecret);

Step 2 - Upload the Excel workbook to cloud storage.

cellsInstance.UploadFile(input_Excel, File.OpenRead(input_Excel));

Step 2 - Upload the Excel workbook to cloud storage.

cellsInstance.UploadFile(input_Excel, File.OpenRead(input_Excel));

Step 3 - Insert Image was Excel watermark.

var response = cellsInstance.CellsWorkbookPutWorkbookBackground(input_Excel, imageBytes, null);

Once processed, your Excel document will display the watermark image in the background.

Remove Excel Watermark in C#

Similarly, when you need to remove an Excel watermark, our REST API provides a seamless solution to accomplish this requirement. So once you have initialized the API, call CellsWorkbookDeleteWorkbookBackground(…) to remove the watermark from Excel workbook.

The above code snippet clears any existing background or watermark, restoring a clean worksheet. You can use it when updating or replacing an existing watermark.

Create Watermark in Excel using cURL Commands

Alternatively, you can also add watermark in Excel directly through the REST API using cURL. This method is ideal for batch operations or integration with web applications.

Step 1 — Generate Access Token:

curl -v "https://api.aspose.cloud/connect/token" \
-X POST \
-d "grant_type=client_credentials&client_id=XXXXXX-XXXXX-XXXXXXXXX-XXXXXXX&client_secret=XXXXXXXXXXXXXX" \
-H "Content-Type: application/x-www-form-urlencoded" \
-H "Accept: application/json"

Step 2 — Upload Excel File:

curl -v "https://api.aspose.cloud/v3.0/cells/storage/file/{filePath}" \
-X PUT \
-F file=@{localFilePath} \
-H "Content-Type: multipart/form-data" \
-H "Authorization: Bearer {ACCESS_TOKEN}"

Step 3 — Add Watermark to Excel:

curl -v "https://api.aspose.cloud/v3.0/cells/{sourceFile}/background" \
-X PUT \
-H  "accept: multipart/form-data" \
-H  "authorization: Bearer {ACCESS_TOKEN}" \
-H  "Content-Type: multipart/form-data" \
-d  "File":{"confidential.png"}

Replace:

  • {ACCESS_TOKEN} with JWT token generated above
  • {sourceFile} input Excel workbook

After execution, your Excel workbook will contain the specified watermark image.

Free Online Watermarking App

If you are interested in trying the capabilities of Cloud API without any coding, then you may try using our Free Online Watermarking App. It’s built using amazing Aspose.Cells Cloud. Simply upload your input Excel workbook and download the watermarked Excel workbook.

watermark excel workbook

Why Use Aspose.Cells Cloud for Excel Watermarking?

  • No Microsoft Excel installation required.
  • Secure and scalable cloud-based processing.
  • Works with all Excel file types — XLS, XLSX, CSV, ODS.
  • Supports image and text-based watermarking.
  • Easy integration with C#, Java, Python, or Node.js apps.

Conclusion

Adding a watermark in Excel not only enhances your document’s appearance but also ensures confidentiality and branding. With Aspose.Cells Cloud SDK for .NET, it’s effortless to add, insert, or remove Excel watermarks programmatically.

You can create, apply, and delete Excel watermarks in bulk, saving time while maintaining consistency across reports and templates.

🔗 Useful Resources

❓ Frequently Asked Questions (FAQs)

Q1: How can I add a watermark to an Excel sheet using C#?
You can use Aspose.Cells Cloud SDK’s CellsWorkbookPutWorkbookBackground() method to upload and apply a watermark image programmatically.

Q2: Can I remove an existing watermark from Excel?
Yes, simply call the CellsWorkbookDeleteWorkbookBackground() method to remove the current watermark.

Q3: Can I create custom text-based watermarks?
Yes. You can design text watermarks by converting text into an image and then applying it to the Excel sheet.

Q4: Is Aspose.Cells Cloud free to use?
You can sign up for a free trial and explore watermark and Excel automation features.

Q5: Does this work for all Excel versions?
Yes, it supports Excel 2007 and later versions (XLS, XLSX, and others).