Free c# QR-Code generator

You can look at Open Source QR Code Library or messagingtoolkit-qrcode. I have not used either of them so I can not speak of their ease to use.

ZXing is an open source project that can detect and parse a number of different barcodes. It can also generate QR-codes. (Only QR-codes, though).

There are a number of variants for different languages: ActionScript, Android (java), C++, C#, IPhone (Obj C), Java ME, Java SE, JRuby, JSP. Support for generating QR-codes comes with some of those: ActionScript, Android, C# and the Java variants.

Generate QR Code Image in ASP.NET Using Google Chart API

Google Chart API returns an image in response to a URL GET or POST request. All the data required to create the graphic is included in the URL, including the image type and size.

var url = string.Format("http://chart.apis.google.com/chart?cht=qr&chs={1}x{2}&chl={0}", txtCode.Text, txtWidth.Text, txtHeight.Text);
WebResponse response = default(WebResponse);
Stream remoteStream = default(Stream);
StreamReader readStream = default(StreamReader);
WebRequest request = WebRequest.Create(url);
response = request.GetResponse();
remoteStream = response.GetResponseStream();
readStream = new StreamReader(remoteStream);
System.Drawing.Image img = System.Drawing.Image.FromStream(remoteStream);
img.Save("D:/QRCode/" + txtCode.Text + ".png");
response.Close();
remoteStream.Close();
readStream.Close();
txtCode.Text = string.Empty;
txtWidth.Text = string.Empty;
txtHeight.Text = string.Empty;
lblMsg.Text = "The QR Code generated successfully";

Click here for complete source code to download

Demo of application for free QR Code generator using C#

Take a look QRCoder - pure C# open source QR code generator. Can be used in three lines of code

QRCodeGenerator qrGenerator = new QRCodeGenerator();
QRCodeGenerator.QRCode qrCode = qrGenerator.CreateQrCode(textBoxQRCode.Text, QRCodeGenerator.ECCLevel.Q);
pictureBoxQRCode.BackgroundImage = qrCode.GetGraphic(20);