How to Scan QR Codes and Barcodes in ASP.NET Core with C#

Scan QR codes and barcodes in ASP.NET Core using C# and Spire.Barcode

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:

Backend logic that processes and decodes uploaded images.
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.

ASP.NET Core QR code and Code128 barcode scan page with recognized results and copy button

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.