Add QR Code to PDF, Excel, PPT, Word Documents, and Images in C#

ChangeQRCodeAppearance.cs

// Change Appearance of QR code in C#
// Setting background color, forecolor, transparency, etc.
Background = new Background()
{
    Color = Color.Black,
    Transparency = 0.5
},
//set text color and Font
ForeColor = Color.White

SignDocsWithQRCode.cs

// Electronically Sign PDF, Excel, PPT, Word Documents and Images with QR Code using GroupDocs.Signature for .NET API
using (Signature signature = new Signature("filePath/document.pdf")) // Provide any DOC, PDF, XLS, PPT, PNG, JPG, WebP file.
{
    // Create QR Code option with predefined text
    QrCodeSignOptions options = new QrCodeSignOptions("Signed by GroupDocs")
    {
        EncodeType = QrCodeTypes.QR,
        // Set QR Code position & appearance
        Left = 50,
        Top = 50,
        Width = 90,
        Height = 90
    };
    // Sign document and save file
    SignResult result = signature.Sign("filePath/document-with-qr-code.pdf", options);
}