Create QR Codes with .NET

QR codes are a simple and very popular way of exchanging data and information - even in .NET. They have become part of everyday life.

Unfortunately, .NET does not natively support the generation of QRCodes; we have to rely on the community. Fortunately, there is a very good library that we can use: QRCoder by Raffael Herrmann .

Install QRCoder

The installation is simple. We can install the library via NuGet:

1dotnet add package QRCoder

Using QRCoder

The structure and use of the library is very simple: we basically just need to create an instance of the QRCodeGenerator class and call the CreateQrCode method. The CreateQrCode method returns a QRCodeData object, which we can then convert into a Bitmap object.

A more realistic example is that we abstract the generation of the QRCode into a provider, which allows us to separate the implementation from the use and also to implement unit tests more easily.

 1// Defining the QRCodeProvider class
 2// Add an interface to your code!
 3public class QRCodeProvider
 4{
 5    // Creating a new instance of QRCodeGenerator
 6    // In principle, this class supports IDisposable, but we can re-use this instance
 7    private static readonly QRCodeGenerator s_qrGenerator = new();
 8
 9    // Method to generate the QR code
10    public byte[] GeneratePng(string text)
11    {
12        // Creating the QR code data with our defaults
13        using QRCodeData qrCodeData = s_qrGenerator.CreateQrCode(text, QRCodeGenerator.ECCLevel.Q);
14
15        // Creating a new instance of PngByteQRCode with the QR code data
16        // We can also use other Image types, like BitmapByteQRCode
17        PngByteQRCode qrCode = new (qrCodeData);
18
19        // Returning the QR code as a graphic
20        return qrCode.GetGraphic(pixelsPerModule: 20);
21    }
22}

The QRCodeProvider class can now either be used directly or integrated cleanly into a dependency injection container with an additional interface.

By calling the provider, we can generate our QRCode as a PNG with a handful of code - in this example stored on the file system.

 1// NuGet: https://github.com/codebude/QRCoder
 2using QRCoder;
 3
 4namespace BenjaminAbt_Samples_QrCode // Defining the namespace
 5{
 6    internal class Program // Defining the Program class
 7    {
 8        static void Main(string[] args)
 9        {
10            // Creating a new instance of QRCodeProvider
11            // This is our own abstraction
12            QRCodeProvider qrCodeProvider = new();
13
14            // Defining the path where the QR code will be saved
15            // You can use different types of images and also svg or In-Memory
16            string path = @"C:\temp\qrcodetest.png";
17
18            string sampleText = "Hello World";
19
20            // Generating the QR code
21            byte[] png = qrCodeProvider.GeneratePng(sampleText);
22
23            File.WriteAllBytes(path, png); // Writing the QR code to the file
24        }
25    }
26
27    // QRCodeProvider here
28}

Create QR Codes with .NET