Generate QR Codes for Free in C#: A Step-by-Step Guide

Introduction

In this exercise, we will learn how to generate QR codes for free in C# using the QRCoder library. QR codes are widely adopted in modern applications for sharing links, payment information, authentication, and more.

With just a few lines of code, you can generate and save QR codes as image files on your local machine. This approach works with .NET 8/.NET 9 and is completely FREE, making it ideal for personal projects, demos, and enterprise solutions.

Step 1: Install the Required NuGet Package

Run the following command in your project directory:

dotnet add package QRCoder

This installs the QRCoder library which provides multiple renderers (PNG, Bitmap, SVG, etc.).

Step 2: Create a QRCodeHelper Class

We'll create a helper class to encapsulate QR code generation. For cross-platform support, we’ll use the built-in PngByteQRCode renderer, which returns PNG bytes directly.

using System;

using System.IO;

using QRCoder;



namespace MyPlaygroundApp.Util

{

    public static class QRCodeHelper

    {

        public static void GenerateToFile(string text, string filePath, int pixelsPerModule = 20)

        {

            using var qrGenerator = new QRCodeGenerator();

            using var qrData = qrGenerator.CreateQrCode(text, QRCodeGenerator.ECCLevel.Q);

            var qrCode = new PngByteQRCode(qrData);



            // Get PNG as byte array

            byte[] pngBytes = qrCode.GetGraphic(pixelsPerModule);



            // Save to file

            File.WriteAllBytes(filePath, pngBytes);

        }

    }

}

Step 3: Implement the Client Code

Now, let’s call our helper from Main() to generate a QR code for a URL:

using MyPlaygroundApp.Utils;



class Program

{

    static void Main(string[] args)

    {

        string url = "https://dev.to";



        string file = @"C:\Users\User\Downloads\devto.png";



        QRCodeHelper.GenerateToFile(url, file);



        Console.WriteLine($"QR code saved to {file}");

    }

}

When you run the program, a QR code image will be saved in the QRCodes folder relative to your project output.

Step 4: Run and See the Result

Build and run your project:

dotnet run

Check the Downloads folder, you'll see a qrcode.png file.

Open it with any image viewer or scan it with your phone’s camera. It should redirect you to

Summary

• We used QRCoder, a free and open-source library, to generate QR codes in C#.


• Created a reusable QRCodeHelper class.


• Generated and saved a QR code as a PNG file.


• With this setup, you can easily extend the helper to generate QR codes for Wi-Fi credentials, payment links, or authentication tokens.

Reference

QRCoder

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