OCR C#: Call an OCR API in .NET to Extract Text and Data

using System.Net.Http.Headers;
using System.Text.Json;

var apiKey = "YOUR_API_KEY";
const string baseUrl = "https://docuocr.com/api/documents";

using var http = new HttpClient();
http.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", apiKey);

// 1. Upload the PDF or image, get a file_id
using var form = new MultipartFormDataContent();
form.Add(new ByteArrayContent(File.ReadAllBytes("invoice.pdf")), "file", "invoice.pdf");
var upload = await http.PostAsync($"{baseUrl}/upload", form);
var fileId = JsonDocument.Parse(await upload.Content.ReadAsStringAsync())
    .RootElement.GetProperty("file_id").GetString();

// 2. Start extraction, get a job hash
var extract = await http.PostAsJsonAsync($"{baseUrl}/extract", new { file_id = fileId });
var hash = JsonDocument.Parse(await extract.Content.ReadAsStringAsync())
    .RootElement.GetProperty("extraction_hash").GetString();

// 3. Poll until the JSON is ready
JsonElement result;
while (true)
{
    var res = await http.GetStringAsync($"{baseUrl}/extraction/{hash}");
    result = JsonDocument.Parse(res).RootElement;
    if (result.GetProperty("status").GetString() == "completed") break;
    await Task.Delay(2000);
}

// result.GetProperty("fields") and ("tables") are ready to use
foreach (var field in result.GetProperty("fields").EnumerateArray())
    Console.WriteLine($"{field.GetProperty("name")}: {field.GetProperty("value")}");