Quickstart: Translate text with C#

In this quickstart, you translate text from one language to another using the Translator Text API.


You'll need Visual Studio 2017 to run this code on Windows. (The free Community Edition will work.)

To use the Translator Text API, you also need a subscription key; see How to sign up for the Translator Text API.

Translate request

The following code translates source text from one language to another using the Translate method.

  1. Create a new C# project in your favorite IDE.
  2. Add the code provided below.
  3. Replace the key value with an access key valid for your subscription.
  4. Run the program.
using System;
using System.Net.Http;
using System.Text;
// NOTE: Install the Newtonsoft.Json NuGet package.
using Newtonsoft.Json;

namespace TranslatorTextQuickStart
    class Program
        static string host = "https://api.cognitive.microsofttranslator.com";
        static string path = "/translate?api-version=3.0";
        // Translate to German and Italian.
        static string params_ = "&to=de&to=it";

        static string uri = host + path + params_;

        // NOTE: Replace this example key with a valid subscription key.
        static string key = "ENTER KEY HERE";

        static string text = "Hello world!";

        async static void Translate()
            System.Object[] body = new System.Object[] { new { Text = text } };
            var requestBody = JsonConvert.SerializeObject(body);

            using (var client = new HttpClient())
            using (var request = new HttpRequestMessage())
                request.Method = HttpMethod.Post;
                request.RequestUri = new Uri(uri);
                request.Content = new StringContent(requestBody, Encoding.UTF8, "application/json");
                request.Headers.Add("Ocp-Apim-Subscription-Key", key);

                var response = await client.SendAsync(request);
                var responseBody = await response.Content.ReadAsStringAsync();
                var result = JsonConvert.SerializeObject(JsonConvert.DeserializeObject(responseBody), Formatting.Indented);

                Console.OutputEncoding = UnicodeEncoding.UTF8;

        static void Main(string[] args)

Translate response

A successful response is returned in JSON as shown in the following example:

    "detectedLanguage": {
      "language": "en",
      "score": 1.0
    "translations": [
        "text": "Hallo Welt!",
        "to": "de"
        "text": "Salve, mondo!",
        "to": "it"

Next steps

Explore the sample code for this quickstart and others, including transliteration and language identification, as well as other sample Translator Text projects on GitHub.