Many business applications today need the ability to scan barcodes and QR codes in ASP.NET environments. From ticket validation and payment processing to inventory management, an ASP.NET QR code scanner or barcode reading feature can greatly improve efficiency and accuracy for both web and enterprise systems.

This tutorial demonstrates how to build a complete solution to scan barcodes in ASP.NET with C# code using Spire.Barcode for .NET. We’ll create an ASP.NET Core web application that can read both QR codes and various barcode formats from uploaded images, delivering high recognition accuracy and easy integration into existing projects.

Guide Overview

• 1. Project Setup
• 2. Implementing QR Code and Barcode Scanning Feature with C# in ASP.NET
• 3. Testing and Troubleshooting
• 4. Extending to Other .NET Applications
• 5. Conclusion

1. Project Setup

Step 1: Create the Project

Create a new ASP.NET Core Razor Pages project, which will serve as the foundation for the scanning feature. Use the following command to create a new project or manually configure it in Visual Studio:

dotnet new webapp -n QrBarcodeScanner
cd QrBarcodeScanner

Step 2: Install Spire.Barcode for .NET

Install the Spire.Barcode for .NET NuGet package, which supports decoding a wide range of barcode types with a straightforward API. Search for the package in the NuGet Package Manager or use the command below to install it:

dotnet add package Spire.Barcode

Spire.Barcode for .NET offers built-in support for both QR codes and multiple barcode formats such as Code128, EAN-13, and Code39, making it suitable for ASP.NET Core integration without requiring additional image processing libraries. To find out all the supported barcode types, refer to the BarcodeType API reference.

You can also use Free Spire.Barcode for .NET for smaller projects.

2. Implementing QR Code and Barcode Scanning Feature with C# in ASP.NET

A reliable scanning feature involves two main parts:

1. Backend logic that processes and decodes uploaded images.
2. A simple web interface that lets users upload files for scanning.

We will first focus on the backend implementation to ensure the scanning process works correctly, then connect it to a minimal Razor Page frontend.

Backend: QR & Barcode Scanning Logic with Spire.Barcode

The backend code reads the uploaded file into memory and processes it with Spire.Barcode, using either a memory stream or a file path. The scanned result is then returned. This implementation supports QR codes and other barcode types without requiring format-specific logic.

Index.cshtml.cs

using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.RazorPages;
using Spire.Barcode;

public class IndexModel : PageModel
{
    [BindProperty]
    public IFormFile Upload { get; set; }  // Uploaded file

    public string Result { get; set; }     // Scanning result
    public string UploadedImageBase64 { get; set; } // Base64 string for preview

    public void OnPost()
    {
        if (Upload != null && Upload.Length > 0)
        {
            using (var ms = new MemoryStream())
            {
                // Read the uploaded file into memory
                Upload.CopyTo(ms);

                // Convert the image to Base64 for displaying in HTML <img>
                UploadedImageBase64 = "data:" + Upload.ContentType + ";base64," +
                                      Convert.ToBase64String(ms.ToArray());

                // Reset the stream position before scanning
                ms.Position = 0;

                // Scan the barcode or QR code from the stream
                try
                {
                    string[] scanned = BarcodeScanner.Scan(ms);
                    // Return the scanned result
                    Result = scanned != null && scanned.Length > 0
                        ? string.Join(", ", scanned)
                        : "No code detected.";
                }
                catch (Exception ex)
                {
                    Result = "Error while scanning: " + ex.Message;
                }
            }
        }
    }
}

Explanation of Key Classes and Methods

• BarcodeScanner: A static class in Spire.Barcode that decodes images containing QR codes or barcodes.
• BarcodeScanner.Scan(Stream imageStream): Scans an uploaded image directly from a memory stream and returns an array of decoded strings. This method scans all barcodes in the given image.
• Supplementary methods (optional):
  • BarcodeScanner.Scan(string imagePath): Scans an image from a file path.
  • BarcodeScanner.ScanInfo(string imagePath): Scans an image from a file path and returns additional barcode information such as type, location, and data.

These methods can be used in different ways, depending on the application requirements.

Frontend: QR & Barcode Upload & Scanning Result Interface

The following page design provides a simple upload form where users can submit an image containing a QR code or barcode. Once uploaded, the image is displayed along with the recognized result, which can be copied with a single click. The layout is intentionally kept minimal for fast testing, yet styled for a clear and polished presentation.

Index.cshtml

@page
@model IndexModel
@{
    ViewData["Title"] = "QR & Barcode Scanner";
}

<div style="max-width:420px;margin:40px auto;padding:20px;border:1px solid #ccc;border-radius:8px;background:#f9f9f9;">
    <h2>QR & Barcode Scanner</h2>
    <form method="post" enctype="multipart/form-data" id="uploadForm">
        <input type="file" name="upload" accept="image/*" required onchange="this.form.submit()" style="margin:10px 0;" />
    </form>

    @if (!string.IsNullOrEmpty(Model.UploadedImageBase64))
    {
        <div style="margin-top:15px;text-align:center;">
            <img src="/@Model.UploadedImageBase64" style="width:300px;height:300px;object-fit:contain;border:1px solid #ddd;background:#fff;" />
        </div>
    }

    @if (!string.IsNullOrEmpty(Model.Result))
    {
        <div style="margin-top:15px;padding:10px;background:#e8f5e9;border-radius:6px;">
            <b>Scan Result:</b>
            <p id="scanText">@Model.Result</p>
            <button type="button" onclick="navigator.clipboard.writeText(scanText.innerText)" style="background:#28a745;color:#fff;padding:6px 10px;border:none;border-radius:4px;">Copy</button>
        </div>
    }
</div>

Below is a screenshot showing the scan page after successfully recognizing both a QR code and a Code128 barcode, with the results displayed and a one-click copy button available.

This ASP.NET Core application can scan QR codes and other barcodes from uploaded images. If you're looking to generate QR codes or barcodes, check out How to Generate QR Codes in ASP.NET Core.

3. Testing and Troubleshooting

After running the application, test the scanning feature with:

• A QR code image containing a URL or plain text.
• A barcode image such as Code128 or EAN-13.

If recognition fails:

• Ensure the image has good contrast and minimal distortion.
• Use images of reasonable resolution (not excessively large or pixelated).
• Test with different file formats such as JPG, PNG, or BMP.
• Avoid images with reflections, glare, or low lighting.
• When scanning multiple barcodes in one image, ensure each code is clearly separated to improve recognition accuracy.

A good practice is to maintain a small library of sample QR codes and barcodes to test regularly after making code changes.

4. Extending to Other .NET Applications

The barcode scanning logic in this tutorial works the same way across different .NET application types — only the way you supply the image file changes. This makes it easy to reuse the core decoding method, BarcodeScanner.Scan(), in various environments such as:

• ASP.NET Core MVC controllers or Web API endpoints
• Desktop applications like WinForms or WPF
• Console utilities for batch processing

Example: Minimal ASP.NET Core Web API Endpoint — receives an image file via HTTP POST and returns decoded results as JSON:

[ApiController]
[Route("api/[controller]")]
public class ScanController : ControllerBase
{
    [HttpPost]
    public IActionResult Scan(IFormFile file)
    {
        if (file == null) return BadRequest("No file uploaded");
        using var ms = new MemoryStream();
        file.CopyTo(ms);
        ms.Position = 0;
        string[] results = BarcodeScanner.Scan(ms);
        return Ok(results);
    }
}

Example: Console application — scans a local image file and prints the decoded text:

string[] result = BarcodeScanner.Scan(@"C:\path\to\image.png");
Console.WriteLine(string.Join(", ", result));

This flexibility makes it simple for developers to quickly add QR code and barcode scanning to new projects or extend existing .NET applications.

5. Conclusion

This tutorial has shown how to implement a complete QR code and barcode scanning solution in ASP.NET Core using Spire.Barcode for .NET. From receiving uploaded images to decoding and displaying the results, the process is straightforward and adaptable to a variety of application types. With this approach, developers can quickly integrate reliable scanning functionality into e-commerce platforms, ticketing systems, document verification tools, and other business-critical web applications.

For more advanced scenarios, Spire.Barcode for .NET provides additional features such as customizing the recognition process, handling multiple image formats and barcode types, and more. Apply for a free trial license to unlock all the advanced features.

Download Spire.Barcode for .NET today and start building your own ASP.NET barcode scanning solution.

QR codes have become a standard feature in modern web applications, widely used for user authentication, contactless transactions, and sharing data like URLs or contact information. For developers working with ASP.NET, implementing QR code generation using C# is a practical requirement in many real-world scenarios.

In this article, you’ll learn how to generate QR codes in ASP.NET using Spire.Barcode for .NET. We’ll walk through a complete example based on an ASP.NET Core Web App (Razor Pages) project, including backend logic and a simple UI to display the generated code. The same approach can be easily adapted to MVC, Web API, and Web Forms applications.

Article Overview

• 1. Project Setup and Dependencies
• 2. Generate QR Code in ASP.NET Using C#
• 3. Customize QR Code Output
• 4. Apply Logic in MVC, Web API, and Web Forms
• 5. Conclusion
• FAQs

1. Project Setup and Dependencies

Prerequisites

To follow along, make sure you have:

• Visual Studio 2019 or newer
• .NET 6 or later
• ASP.NET Core Web App (Razor Pages Template)
• NuGet package: Spire.Barcode for .NET

Install Spire.Barcode for .NET

Install the required library using NuGet Package Manager Console:

Install-Package Spire.Barcode

Spire.Barcode is a fully self-contained .NET barcode library that supports in-memory generation of QR codes without external APIs. You can also use Free Spire.Barcode for .NET for smaller projects.

2. Generate QR Code in ASP.NET Using C#

This section describes how to implement QR code generation in an ASP.NET Core Web App (Razor Pages) project. The example includes a backend C# handler that generates the QR code using Spire.Barcode for .NET, and a simple Razor Page frontend for user input and real-time display.

Step 1: Add QR Code Generation Logic in PageModel

The backend logic resides in the Index.cshtml.cs file. It processes the form input, generates a QR code using Spire.Barcode, and returns the result as a Base64-encoded image string that can be directly embedded in HTML.

using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.RazorPages;
using Spire.Barcode;

public class IndexModel : PageModel
{
    [BindProperty]
    public string InputData { get; set; }

    public string QrCodeBase64 { get; set; }

    public void OnPost()
    {
        if (!string.IsNullOrWhiteSpace(InputData))
        {
            QrCodeBase64 = GenerateQrCodeBase64(InputData);
        }
    }
    
    private string GenerateQrCodeBase64(string input)
    {
        var settings = new BarcodeSettings
        {
            Type = BarCodeType.QRCode,            // QR code type
            Data = input,                         // Main encoded data
            Data2D = input,                       // Required for 2D barcode, usually same as Data
            QRCodeDataMode = QRCodeDataMode.Byte, // Byte mode (supports multilingual content)
            QRCodeECL = QRCodeECL.M,              // Medium error correction (15%)
            X = 3,                                // Module size (affects image dimensions)
            ShowText = false,                     // Hide default barcode text
            ShowBottomText = true,                // Show custom bottom text
            BottomText = input                    // Bottom text to display under the QR code
        };

        var generator = new BarCodeGenerator(settings);
        using var ms = new MemoryStream();
        var qrImage = generator.GenerateImage();
        qrImage.Save(ms, System.Drawing.Imaging.ImageFormat.Png);
        return Convert.ToBase64String(ms.ToArray());
    }
}

Key Components:

• BarcodeSettings: Specifies the QR code's core configuration, such as type (QRCode), data content, encoding mode, and error correction level.

• BarCodeGenerator: Takes the settings and generates the QR code image as a System.Drawing.Image object using the GenerateImage() method.

• Base64 Conversion: Converts the image to a Base64 string so it can be directly embedded into the HTML page without saving to disk.

This approach keeps the entire process in memory, making it fast, portable, and suitable for serverless or cloud-hosted applications.

Step 2: Create the Razor Page for User Input and QR Code Display and Download

The following Razor markup in the Index.cshtml file defines a form for entering text or URLs, displays the generated QR code upon submission, and provides a button to download the QR code image.

@page
@model IndexModel
@{
    ViewData["Title"] = "QR Code Generator";
}

<h2>QR Code Generator</h2>

<form method="post">
    <label for="InputData">Enter text or URL:</label>
    <input type="text" id="InputData" name="InputData" style="width:300px;" required />
    <button type="submit">Generate QR Code</button>
</form>

@if (!string.IsNullOrEmpty(Model.QrCodeBase64))
{
    <div style="margin-top:20px">
        <img src="data:image/png;base64,@Model.QrCodeBase64" alt="QR Code" />
        <br />
        <a href="data:image/png;base64,@Model.QrCodeBase64" download="qrcode.png">Download QR Code</a>
    </div>
}

The Base64-encoded image is displayed directly in the browser using a data: URI. This eliminates the need for file storage and allows for immediate rendering and download.

The following screenshot shows the result after submitting text input.

If you need to scan QR codes instead, please refer to How to Scan QR Codes in C#.

3. Customize QR Code Output

Spire.Barcode provides several customization options through the BarcodeSettings class to control the appearance and behavior of the generated QR code:

These properties help you tailor the appearance of your QR code for branding, readability, or user interaction purposes.

To explore more QR code settings, refer to the BarcodeSettings API reference.

4. Apply Logic in MVC, Web API, and Web Forms

The same QR code generation logic used in Razor Pages can also be reused in other ASP.NET frameworks such as MVC, Web API, and Web Forms.

MVC Controller Action

In an MVC project, you can add a Generate action in a controller (e.g., QrController.cs) to generate and return the QR code image directly:

public class QrController : Controller
{
    public ActionResult Generate(string data)
    {
        var settings = new BarcodeSettings
        {
            Type = BarCodeType.QRCode,
            Data = data,
            QRCodeDataMode = QRCodeDataMode.Byte,
            QRCodeECL = QRCodeECL.M,
            X = 5
        };

        var generator = new BarCodeGenerator(settings);
        using var ms = new MemoryStream();
        generator.GenerateImage().Save(ms, System.Drawing.Imaging.ImageFormat.Png);
        return File(ms.ToArray(), "image/png");
    }
}

This method returns the QR code as a downloadable PNG file, ideal for server-side rendering.

Web API Endpoint

For Web API, you can define a GET endpoint in a controller such as QrApiController.cs that responds with the generated image stream:

[ApiController]
[Route("api/[controller]")]
public class QrApiController : ControllerBase
{
    [HttpGet("generate")]
    public IActionResult GetQr(string data)
    {
        var settings = new BarcodeSettings
        {
            Type = BarCodeType.QRCode,
            Data = data
        };

        var generator = new BarCodeGenerator(settings);
        using var ms = new MemoryStream();
        generator.GenerateImage().Save(ms, System.Drawing.Imaging.ImageFormat.Png);
        return File(ms.ToArray(), "image/png");
    }
}

This approach is suitable for frontends built with React, Vue, Angular, or any JavaScript framework.

Web Forms Code-Behind

In ASP.NET Web Forms, you can handle QR code generation in the code-behind of a page like Default.aspx.cs:

protected void btnGenerate_Click(object sender, EventArgs e)
{
    var settings = new BarcodeSettings
    {
        Type = BarCodeType.QRCode,
        Data = txtInput.Text
    };

    var generator = new BarCodeGenerator(settings);
    using var ms = new MemoryStream();
    generator.GenerateImage().Save(ms, System.Drawing.Imaging.ImageFormat.Png);
    imgQR.ImageUrl = "data:image/png;base64," + Convert.ToBase64String(ms.ToArray());
}

The generated image is embedded directly into an asp:Image control using a Base64 data URI.

5. Conclusion

With Spire.Barcode for .NET, you can seamlessly generate and customize QR codes across all ASP.NET project types — Razor Pages, MVC, Web API, or Web Forms. The solution is fully offline, fast, and requires no third-party API.

Returning images as Base64 strings simplifies deployment and avoids file management. Whether you're building authentication tools, ticketing systems, or contact sharing, this approach is reliable and production-ready.

FAQs

Q: Does Spire.Barcode support Unicode characters like Chinese or Arabic?

A: Yes. Use QRCodeDataMode.Byte for full Unicode support.

Q: Can I adjust QR code size and color?

A: Absolutely. Use properties like X, ForeColor, and ImageWidth.

Q: Is this solution fully offline?

A: Yes. It works without any external API calls or services.

Q: Can I expose this QR logic via API?

A: Yes. Use ASP.NET Web API to serve generated images to client apps.