Quickstart: Use the Translator Text API to detect text language using C#

In this quickstart, you'll learn how to detect the language of provided text using .NET Core and the Translator Text REST API.

This quickstart requires an Azure Cognitive Services account with a Translator Text resource. If you don't have an account, you can use the free trial to get a subscription key.


Create a .NET Core project

Open a new command prompt (or terminal session) and run these commands:

dotnet new console -o detect-sample
cd detect-sample

The first command does two things. It creates a new .NET console application, and creates a directory named detect-sample. The second command changes to the directory for your project.

Next, you'll need to install Json.Net. From your project's directory, run:

dotnet add package Newtonsoft.Json --version 11.0.2

Add required namespaces to your project

The dotnet new console command that you ran earlier created a project, including Program.cs. This file is where you'll put your application code. Open Program.cs, and replace the existing using statements. These statements ensure that you have access to all the types required to build and run the sample app.

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

Create a function to detect the source text's language

Within the Program class, create a function called Detect. This class encapsulates the code used to call the Detect resource and prints the result to console.

static void Detect()
   * The code for your call to the translation service will be added to this
   * function in the next few sections.

Set the subscription key, host name, and path

Add these lines to the Detect function.

string host = "https://api.cognitive.microsofttranslator.com";
string route = "/detect?api-version=3.0";
string subscriptionKey = "YOUR_SUBSCRIPTION_KEY";

Next, we need to create and serialize the JSON object that includes the text that will undergo language detection.

System.Object[] body = new System.Object[] { new { Text = @"Salve mondo!" } };
var requestBody = JsonConvert.SerializeObject(body);

Instantiate the client and make a request

These lines instantiate the HttpClient and the HttpRequestMessage:

using (var client = new HttpClient())
using (var request = new HttpRequestMessage())
  // In the next few sections you'll add code to construct the request.

Construct the request and print the response

Inside the HttpRequestMessage you'll:

  • Declare the HTTP method
  • Construct the request URI
  • Insert the request body (serialized JSON object)
  • Add required headers
  • Make an asynchronous request
  • Print the response

Add this code to the HttpRequestMessage:

// Set the method to POST
request.Method = HttpMethod.Post;

// Construct the full URI
request.RequestUri = new Uri(host + route);

// Add the serialized JSON object to your request
request.Content = new StringContent(requestBody, Encoding.UTF8, "application/json");

// Add the authorization header
request.Headers.Add("Ocp-Apim-Subscription-Key", subscriptionKey);

// Send request, get response
var response = client.SendAsync(request).Result;
var jsonResponse = response.Content.ReadAsStringAsync().Result;

// Pretty print the response
Console.WriteLine("Press any key to continue.");

To print the response with "Pretty Print" (formatting for the response), add this function to your Program class:

static string PrettyPrint(string s)
    return JsonConvert.SerializeObject(JsonConvert.DeserializeObject(s), Formatting.Indented);

Put it all together

The last step is to call Detect() in the Main function. Locate static void Main(string[] args) and add these lines:


Run the sample app

That's it, you're ready to run your sample app. From the command line (or terminal session), navigate to your project directory and run:

dotnet run

Sample response

Find the country abbreviation in this list of languages.

    "language": "it",
    "score": 1.0,
    "isTranslationSupported": true,
    "isTransliterationSupported": false,
    "alternatives": [
        "language": "pt",
        "score": 1.0,
        "isTranslationSupported": true,
        "isTransliterationSupported": false
        "language": "en",
        "score": 1.0,
        "isTranslationSupported": true,
        "isTransliterationSupported": false

Clean up resources

Make sure to remove any confidential information from your sample app's source code, like subscription keys.

Next steps

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

See also