The Best C# API for Global License Plate OCR (Free Image Testing)

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// 👉 https://structocr.com/register

using System;
using System.IO;
using System.Net.Http;
using System.Text;
using System.Text.Json;
using System.Threading.Tasks;

namespace StructOCR_Client
{
    class Program
    {
        static async Task Main(string[] args)
        {
            string apiKey = "YOUR_API_KEY"; // Replace with your actual API key
            string imagePath = "path/to/your/vehicle_image.jpg"; // Replace with the path to your image

            // 1. Read image and encode to Base64
            byte[] fileBytes = File.ReadAllBytes(imagePath);
            string base64Img = Convert.ToBase64String(fileBytes);

            // 2. Create JSON payload
            var payload = new { img = base64Img };
            string jsonPayload = JsonSerializer.Serialize(payload);

            // 3. Build the HTTP request (Requires application/json)
            using var client = new HttpClient();
            using var request = new HttpRequestMessage(HttpMethod.Post, "https://api.structocr.com/v1/license-plate");
            
            request.Headers.Add("x-api-key", apiKey);
            request.Content = new StringContent(jsonPayload, Encoding.UTF8, "application/json");

            Console.WriteLine("Uploading Base64 image to StructOCR API...");

            // 4. Send the request and receive the response
            HttpResponseMessage response = await client.SendAsync(request);
            string responseBody = await response.Content.ReadAsStringAsync();

            // 5. Parse the JSON response
            using JsonDocument doc = JsonDocument.Parse(responseBody);
            JsonElement root = doc.RootElement;

            // 6. Extract the License Plate data
            if (root.TryGetProperty("success", out JsonElement successVal) && successVal.GetBoolean())
            {
                JsonElement data = root.GetProperty("data");
                Console.WriteLine("✅ Extraction Successful!");
                Console.WriteLine("Plates Detected: " + data.GetProperty("plates").GetArrayLength());
                
                string countryGuess = data.GetProperty("country_guess").ValueKind == JsonValueKind.Null 
                    ? "N/A" 
                    : data.GetProperty("country_guess").GetString();
                
                Console.WriteLine("Country Guess: " + countryGuess);
                Console.WriteLine("Confidence: " + data.GetProperty("confidence").GetString());
                Console.WriteLine("\n--- Raw Data ---");
                Console.WriteLine(JsonSerializer.Serialize(data, new JsonSerializerOptions { WriteIndented = true }));
            }
            else
            {
                string errorCode = root.TryGetProperty("code", out JsonElement code) ? code.GetString() : "Unknown Code";
                string errorMsg = root.TryGetProperty("message", out JsonElement msg) ? msg.GetString() : "Unknown Error";
                Console.WriteLine($"❌ Error [{errorCode}]: {errorMsg}");
            }
        }
    }
}