QR Code .NET Core: Read and Generate QR Codes in C#

How Do You Install the QR Code Library?

Installing IronQR via NuGet takes seconds. Open Visual Studio, go to Tools > NuGet Package Manager > Manage NuGet Packages for Solution, search for IronQR, and click Install. The package has minimal dependencies and targets Windows, macOS, and Linux out of the box.

Install-Package IronQR

IronQR targets .NET Core 6, 7, 8, 9, and 10, as well as .NET Framework 4.6.2 and later. For cross-platform projects, a SkiaSharp integration handles image processing on non-Windows runtimes. The library works with ASP.NET Core web applications, console apps, and desktop solutions without additional runtime configuration. Once installed, all necessary extension methods and types are available immediately.

How Do You Read a Basic QR Code from an Image?

Reading QR code data from image files requires only a few lines of code. The QrReader class uses an advanced machine learning model that evaluates image quality and selects the correct segment mode automatically, giving you accurate results even when the input image is not ideal.

using IronQr;
using IronSoftware.Drawing;

// Load image containing QR code
var inputBmp = AnyBitmap.FromFile("qr-sample.png");
// Create QrImageInput from the bitmap
QrImageInput imageInput = new QrImageInput(inputBmp);
// Initialize QR Reader with ML model
QrReader reader = new QrReader();
// Read and decode all QR codes in the image
IEnumerable<QrResult> results = reader.Read(imageInput);
// Output decoded text strings
foreach (var qrCode in results)
{
    Console.WriteLine($"QR Code Value: {qrCode.Value}");
    Console.WriteLine($"URL: {qrCode.Url}");
}

using IronQr;
using IronSoftware.Drawing;

// Load image containing QR code
var inputBmp = AnyBitmap.FromFile("qr-sample.png");
// Create QrImageInput from the bitmap
QrImageInput imageInput = new QrImageInput(inputBmp);
// Initialize QR Reader with ML model
QrReader reader = new QrReader();
// Read and decode all QR codes in the image
IEnumerable<QrResult> results = reader.Read(imageInput);
// Output decoded text strings
foreach (var qrCode in results)
{
    Console.WriteLine($"QR Code Value: {qrCode.Value}");
    Console.WriteLine($"URL: {qrCode.Url}");
}

How Do You Extract Advanced QR Code Data?

Beyond basic value decoding, IronQR exposes coordinates, raw data segments, and module-level information from each scanned symbol. This is essential for document processing workflows where you need to know exactly where a QR code appeared on the page, or for applications that must handle multiple codes in a single image.

using IronQr;
using IronSoftware.Drawing;

var inputBmp = AnyBitmap.FromFile("document-with-qr.png");
QrImageInput imageInput = new QrImageInput(inputBmp);
QrReader reader = new QrReader();
IEnumerable<QrResult> results = reader.Read(imageInput);
foreach (var qrCode in results)
{
    // Access decoded value
    Console.WriteLine($"Data: {qrCode.Value}");
    // Get corner coordinate positions
    foreach (PointF point in qrCode.Points)
    {
        Console.WriteLine($"Position: {point.X}, {point.Y}");
    }
}

using IronQr;
using IronSoftware.Drawing;

var inputBmp = AnyBitmap.FromFile("document-with-qr.png");
QrImageInput imageInput = new QrImageInput(inputBmp);
QrReader reader = new QrReader();
IEnumerable<QrResult> results = reader.Read(imageInput);
foreach (var qrCode in results)
{
    // Access decoded value
    Console.WriteLine($"Data: {qrCode.Value}");
    // Get corner coordinate positions
    foreach (PointF point in qrCode.Points)
    {
        Console.WriteLine($"Position: {point.X}, {point.Y}");
    }
}

How Do Error Correction Levels Affect QR Code Quality?

Error correction is the mechanism that allows a QR scanner to recover the original data even when part of the code is obscured, printed poorly, or physically damaged. The QR Code standard defines four levels -- Low (L), Medium (M), Quartile (Q), and High (H) -- each trading storage capacity for damage tolerance.

When generating QR codes, specifying a higher error correction level ensures the output holds up under real scanning conditions:

using IronQr;
using IronSoftware.Drawing;

// Configure QR options with high error correction
var qrOptions = new QrOptions(QrErrorCorrectionLevel.High, 20);
// Generate a QR code with specified error correction
QrCode myQr = QrWriter.Write("https://ironsoftware.com", qrOptions);
// Save as PNG image
AnyBitmap qrImage = myQr.Save();
qrImage.SaveAs("high-error-correction-qr.png");

using IronQr;
using IronSoftware.Drawing;

// Configure QR options with high error correction
var qrOptions = new QrOptions(QrErrorCorrectionLevel.High, 20);
// Generate a QR code with specified error correction
QrCode myQr = QrWriter.Write("https://ironsoftware.com", qrOptions);
// Save as PNG image
AnyBitmap qrImage = myQr.Save();
qrImage.SaveAs("high-error-correction-qr.png");

How Do You Generate QR Codes with International Characters?

IronQR supports the full range of QR encoding modes: numeric, alphanumeric, byte, and Kanji. For Japanese text and other Unicode content, the library selects the most space-efficient encoding automatically:

using IronQr;
using IronSoftware.Drawing;

// Generate QR that encodes Japanese Unicode text
QrCode japaneseQr = QrWriter.Write("こんにちは世界");
// The library selects Kanji mode automatically
AnyBitmap qrImage = japaneseQr.Save();
qrImage.SaveAs("japanese-qr.png");

using IronQr;
using IronSoftware.Drawing;

// Generate QR that encodes Japanese Unicode text
QrCode japaneseQr = QrWriter.Write("こんにちは世界");
// The library selects Kanji mode automatically
AnyBitmap qrImage = japaneseQr.Save();
qrImage.SaveAs("japanese-qr.png");

How Do You Use Payload Generators for Structured QR Data?

A QR code that encodes a plain URL works for simple link sharing, but many applications need to encode structured data -- WiFi credentials, contact cards in vCard format, or event data. Formatting these payloads manually is error-prone; a missing semicolon or incorrect field order will cause scanners to misinterpret the data.

IronQR provides payload helpers that build these structured strings correctly:

using IronQr;
using IronSoftware.Drawing;

// Generate QR code with URL payload
var urlQrCode = QrWriter.Write("https://ironsoftware.com/csharp/qr/");
// Save QR as PNG image file
AnyBitmap qrImage = urlQrCode.Save();
qrImage.SaveAs("url-qr-code.png");
Console.WriteLine("QR code generated successfully.");

using IronQr;
using IronSoftware.Drawing;

// Generate QR code with URL payload
var urlQrCode = QrWriter.Write("https://ironsoftware.com/csharp/qr/");
// Save QR as PNG image file
AnyBitmap qrImage = urlQrCode.Save();
qrImage.SaveAs("url-qr-code.png");
Console.WriteLine("QR code generated successfully.");

How Do You Customize QR Code Appearance?

IronQR gives you control over the visual appearance of generated codes without sacrificing scannability. You can change the foreground and background colors, apply custom branding, or embed a logo into the quiet zone at the centre.

using IronQr;
using IronSoftware.Drawing;

// Define custom colors for the QR code
var darkColor = Color.FromArgb(30, 30, 120);   // Deep navy foreground
var lightColor = Color.White;

var options = new QrOptions(QrErrorCorrectionLevel.High, maxVersion: 20)
{
    BackgroundColor = lightColor,
    Color = darkColor,
    // Embed a logo image into the QR center
    Logo = AnyBitmap.FromFile("logo.png")
};

QrCode styledQr = QrWriter.Write("https://ironsoftware.com/csharp/qr/", options);
AnyBitmap output = styledQr.Save();
output.SaveAs("branded-qr.png");

using IronQr;
using IronSoftware.Drawing;

// Define custom colors for the QR code
var darkColor = Color.FromArgb(30, 30, 120);   // Deep navy foreground
var lightColor = Color.White;

var options = new QrOptions(QrErrorCorrectionLevel.High, maxVersion: 20)
{
    BackgroundColor = lightColor,
    Color = darkColor,
    // Embed a logo image into the QR center
    Logo = AnyBitmap.FromFile("logo.png")
};

QrCode styledQr = QrWriter.Write("https://ironsoftware.com/csharp/qr/", options);
AnyBitmap output = styledQr.Save();
output.SaveAs("branded-qr.png");

Embedding a logo reduces the effective data area, so the library requires error correction level H when a logo is provided. The reserved quiet zone at the centre accounts for roughly 30% of the code surface, which is within the recovery capacity of the H level. The library enforces this constraint automatically -- if you set a lower error correction level alongside a logo, IronQR raises an exception with a descriptive message rather than producing a code that scans unreliably.

For ASP.NET Core applications, the ASP.NET Core QR code generator tutorial shows how to serve generated QR codes as image responses from a controller action. The output stream writes directly to the response without intermediate file I/O, which keeps latency low for high-traffic endpoints.

How Do You Read QR Codes in an ASP.NET Core Application?

Scanning QR codes server-side -- from uploaded images, document processing pipelines, or automated inspection systems -- is a common use case for the reading API. The ASP.NET QR code scanner guide covers the full controller and service setup, but the core reading pattern is the same as a console application:

using IronQr;
using IronSoftware.Drawing;
using Microsoft.AspNetCore.Mvc;

[ApiController]
[Route("api/qr")]
public class QrScanController : ControllerBase
{
    [HttpPost("scan")]
    public IActionResult Scan(IFormFile imageFile)
    {
        using var stream = imageFile.OpenReadStream();
        var bitmap = AnyBitmap.FromStream(stream);
        var imageInput = new QrImageInput(bitmap);
        var reader = new QrReader();
        var results = reader.Read(imageInput);

        var decoded = results.Select(r => new { r.Value, r.Url }).ToList();
        return Ok(decoded);
    }
}

using IronQr;
using IronSoftware.Drawing;
using Microsoft.AspNetCore.Mvc;

[ApiController]
[Route("api/qr")]
public class QrScanController : ControllerBase
{
    [HttpPost("scan")]
    public IActionResult Scan(IFormFile imageFile)
    {
        using var stream = imageFile.OpenReadStream();
        var bitmap = AnyBitmap.FromStream(stream);
        var imageInput = new QrImageInput(bitmap);
        var reader = new QrReader();
        var results = reader.Read(imageInput);

        var decoded = results.Select(r => new { r.Value, r.Url }).ToList();
        return Ok(decoded);
    }
}

The AnyBitmap.FromStream() method accepts any readable stream, so the same code path works for files uploaded through a form, images fetched from blob storage, or frames extracted from a video pipeline. The controller does not write any temporary files to disk, which matters for containerized deployments where the filesystem may be read-only.

For high-throughput scenarios, instantiate QrReader once per application lifetime as a singleton, since the ML model loading cost is paid on first construction. Subsequent Read() calls on the same instance are thread-safe and share the loaded model.

How Do You Generate QR Codes in a .NET MAUI Application?

The .NET MAUI QR code tutorial demonstrates full cross-platform generation on iOS, Android, macOS, and Windows. IronQR uses the SkiaSharp rendering backend when running on non-Windows platforms, giving consistent output across all MAUI targets.

using IronQr;
using IronSoftware.Drawing;

// Generate QR and convert to a byte array for display in MAUI
QrCode qr = QrWriter.Write("https://ironsoftware.com/csharp/qr/");
AnyBitmap bitmap = qr.Save();
byte[] imageBytes = bitmap.ExportBytes();

// Bind imageBytes to an <Image Source> in your MAUI page

using IronQr;
using IronSoftware.Drawing;

// Generate QR and convert to a byte array for display in MAUI
QrCode qr = QrWriter.Write("https://ironsoftware.com/csharp/qr/");
AnyBitmap bitmap = qr.Save();
byte[] imageBytes = bitmap.ExportBytes();

// Bind imageBytes to an <Image Source> in your MAUI page

On mobile targets, ExportBytes() returns a PNG byte array that you can feed directly into a StreamImageSource or write to an ImageButton. The MAUI scaffold requires no platform-specific code paths -- the same generation logic runs identically on all four MAUI targets.

For VB.NET projects the API surface is identical; only the syntax differs. The library ships a single NuGet package with no separate VB.NET assembly required.

What Are Your Next Steps?

IronQR covers the complete QR code lifecycle in .NET -- from basic generation and structured payload encoding to ML-powered reading of damaged or branded codes. The library handles Kanji encoding, error correction configuration, and cross-platform image output, leaving you to focus on the logic that is specific to your application.

To put what you have learned into practice:

• Review the C# QR code reader tutorial for a deeper look at the reading API and result processing.
• Work through the C# QR code generator application tutorial for a complete project walkthrough.
• Browse the code examples to see additional generation and reading patterns.
• Purchase an IronQR license to unlock all features for production deployment, or extend the free trial if you need more evaluation time.