QR Code Generator in C# (.NET) using QRCoder

QR Code Generator in C# (.NET) with the QRCoder Library

QR codes have become an integral part of the modern web and mobile applications. They are used for quickly sharing links, contact information, Wi-Fi passwords, payment details, and much more. In the C# (.NET) ecosystem, one of the most popular and easy-to-use libraries for generating QR codes is QRCoder. In this article, we will thoroughly cover how to install the library, create a simple and complex QR code, and save it in various formats (PNG, SVG).

What is QRCoder?

QRCoder is a lightweight, high-performance open-source library for .NET (supports .NET Framework 4.6+ and .NET Core/.NET 5+). It requires no external dependencies except the standard System.Drawing library for raster images. Key features:

• Generate QR codes from text, URLs, contacts (vCard), Wi-Fi settings, SMS, email, and other formats.
• Configure error correction level (L, M, Q, H).
• Select QR code version (matrix size).
• Export to PNG, BMP, SVG, XAML, EPS, PostScript, and HTML.
• Support for colors, background, transparency, and custom logos.

Installation in a C# Project

Installing the QRCoder library is done via the NuGet Package Manager. Open the Package Manager Console or use the .NET CLI:

dotnet add package QRCoder

Or via the Package Manager Console:

Install-Package QRCoder

Basic Example — Generating a Simple QR Code

Let's create a console application that generates a QR code for the string "https://pythonlib.ru" and saves it to a PNG file.

using QRCoder;using System.Drawing;

string url = "https://pythonlib.ru";QRCodeGenerator qrGenerator = new QRCodeGenerator();QRCodeData qrCodeData = qrGenerator.CreateQrCode(url, QRCodeGenerator.ECCLevel.Q);QRCode qrCode = new QRCode(qrCodeData);

// Generate image (pixels)Bitmap qrCodeImage = qrCode.GetGraphic(20);

// Save to fileqrCodeImage.Save("qrcode.png", System.Drawing.Imaging.ImageFormat.Png);

Console.WriteLine("QR code created: qrcode.png");

In this example:

• ECCLevel.Q — error correction level (25% of data can be damaged).
• GetGraphic(20) — size of one module (square) in pixels.
• The result is a black-and-white PNG.

Customizing Appearance — Color, Logo, SVG

QRCoder allows flexible customization of the QR code's appearance. Let's look at an example with a colored background, dark modules, and an embedded logo.

using QRCoder;using System.Drawing;

string data = "https://pythonlib.ru";QRCodeGenerator qrGenerator = new QRCodeGenerator();QRCodeData qrCodeData = qrGenerator.CreateQrCode(data, QRCodeGenerator.ECCLevel.Q);QRCode qrCode = new QRCode(qrCodeData);

// Color settingsColor darkColor = Color.FromArgb(52, 73, 94);   // dark blueColor lightColor = Color.FromArgb(236, 240, 241); // light gray

// Generate with logo (logo must be centered)Bitmap logo = new Bitmap("logo.png");Bitmap qrCodeImage = qrCode.GetGraphic(20, darkColor, lightColor, logo);

qrCodeImage.Save("qrcode_color.png", System.Drawing.Imaging.ImageFormat.Png);Console.WriteLine("Colored QR code with logo saved.");

Note: for proper operation with a logo, it is recommended to use the error correction level ECCLevel.Q or ECCLevel.H, as the logo covers part of the data.

Export to SVG (Vector Format)

If you need a scalable QR code (e.g., for printing), use the SVG renderer. To do this, install the additional package QRCoder.Svg: