Receipt OCR Using c-sharp [A Complete Guide 2025]

In this blog post, we’ll walk through how to integrate the Tabscanner API into a C# application to process receipts
and retrieve structured data in JSON format. We’ll expand the program incrementally with explanations and code
snippets.

Step 1: Set Up the Project

First, create a new .NET console application:

1. Open a terminal or IDE.
2. Create a new project:

   dotnet new console -n TabscannerIntegration
   cd TabscannerIntegration

3. Add the Newtonsoft.Json package for handling JSON:

   dotnet add package Newtonsoft.Json

Step 2: Define API Configuration

Tabscanner’s API requires an API key and endpoints for uploading receipts and polling results. Add these as constants
in the program:

private static readonly string API_KEY = Environment.GetEnvironmentVariable("TABSCANNER_API_KEY");
private static readonly string PROCESS_ENDPOINT = "https://api.tabscanner.com/api/2/process";
private static readonly string RESULT_ENDPOINT_BASE = "https://api.tabscanner.com/api/result/";
    

Replace TABSCANNER_API_KEY with your actual API key (or set it in the environment).

Step 3: Upload a Receipt

The first step is to upload a receipt image to the Tabscanner API. This function takes the image path, sends it as
multipart/form-data, and retrieves a token to poll for results.

private static async Task<string> UploadReceiptAsync(string filePath)
{
    using (var client = new HttpClient())
    using (var fileContent = new MultipartFormDataContent())
    {
        var request = new HttpRequestMessage(HttpMethod.Post, PROCESS_ENDPOINT);
        request.Headers.Add("apikey", API_KEY);

        var fileStreamContent = new StreamContent(File.OpenRead(filePath));
        fileStreamContent.Headers.ContentType = new MediaTypeHeaderValue("image/jpeg");
        fileContent.Add(fileStreamContent, "file", "receipt.jpg");

        request.Content = fileContent;

        var response = await client.SendAsync(request);

        if (response.IsSuccessStatusCode)
        {
            var json = await response.Content.ReadAsStringAsync();
            var token = JObject.Parse(json)["token"]?.ToString();
            Console.WriteLine($"Token received: {token}");
            return token;
        }
        else
        {
            Console.WriteLine($"Error uploading receipt: {response.StatusCode}, {response.ReasonPhrase}");
            return null;
        }
    }
}
    

Step 4: Poll for Results

Once the receipt is uploaded, use the token to poll the Tabscanner API until the receipt processing is complete. Add
the following function to the program:

private static async Task<JObject> PollForResultAsync(string token)
{
    var pollingUrl = $"{RESULT_ENDPOINT_BASE}{token}";

    using (var client = new HttpClient())
    {
        client.DefaultRequestHeaders.Add("apikey", API_KEY);
        
        while (true)
        {
            var response = await client.GetAsync(pollingUrl);

            if (response.IsSuccessStatusCode)
            {
                var json = await response.Content.ReadAsStringAsync();
                var resultData = JObject.Parse(json);
                var status = resultData["status"]?.ToString();

                if (status == "done")
                {
                    Console.WriteLine("Processing complete!");
                    return resultData["result"] as JObject;
                }
                else if (status == "pending")
                {
                    Console.WriteLine("Processing... retrying in 1 second.");
                    await Task.Delay(1000);
                }
                else
                {
                    Console.WriteLine($"Unexpected status: {status}");
                    return null;
                }
            }
            else
            {
                Console.WriteLine($"Error polling for result: {response.StatusCode}, {response.ReasonPhrase}");
                return null;
            }
        }
    }
}
    

Step 5: Integrate and Test

Combine the two functions into the Main method. Provide the path to a sample receipt image and run the
program:

static async Task Main(string[] args)
{
    string filePath = "sample_receipt.jpg";
    Console.WriteLine("Uploading receipt...");
    var token = await UploadReceiptAsync(filePath);

    if (string.IsNullOrEmpty(token))
    {
        Console.WriteLine("Failed to start receipt processing.");
        return;
    }

    Console.WriteLine("Polling for results...");
    var result = await PollForResultAsync(token);

    if (result != null)
    {
        Console.WriteLine("Receipt Data Retrieved:");
        Console.WriteLine(result.ToString(Newtonsoft.Json.Formatting.Indented));
    }
    else
    {
        Console.WriteLine("Failed to retrieve receipt data.");
    }
}
    

Step 6: Run the Program

1. Place a receipt image (e.g., sample_receipt.jpg) in the project directory.
2. Build and run the program:

   dotnet run

3. View the token, polling updates, and final receipt data.

Example Output

When the processing completes, the program will display structured receipt data in JSON format:

{
  "establishment": "SuperMart",
  "date": "2025-01-01 14:32:00",
  "total": 45.67,
  "subTotal": 41.23,
  "tax": 4.44,
  "lineItems": [
    {"desc": "Apple", "qty": 3, "price": 1.5, "lineTotal": 4.5},
    {"desc": "Milk", "qty": 1, "price": 2.5, "lineTotal": 2.5}
  ]
}
    

Conclusion

Tabscanner simplifies receipt data extraction with its powerful OCR API. This step-by-step guide shows how to:

• Upload a receipt.
• Poll for results.
• Retrieve structured JSON data.

With this integration, you can automate receipt processing and streamline workflows in your applications. 🚀

Happy coding!

CLICK HERE TO START USING TABSCANNER API