callvb Tutorials.DeepLClient.SetApiKey "&ltDeepL-Api-Key>"
pushbutton (20,1) "Translate" process="translate_text.txt"
text (22,1) "english"
TextBox (20,13) (25,100) name="translate_this"
text (27,1) "german"
TextBox (26,13) (31,100) name="translated_text"

callvb text = Tutorials.DeepLClient.translate "&Text[translate_this]" "de"

Set Text[translated_text] "&V[text]"
return

Imports System
Imports System.Net.Http
Imports System.Text
Imports System.Text.Json
Imports System.Threading.Tasks

Public Class DeepLClient

    Private ReadOnly _httpClient As HttpClient
    Private _apiKey As String
    Private apiKeySet As Boolean = False

    Public Sub New()
        _httpClient = New HttpClient()
    End Sub

    Public Sub SetAPIKey(apiKey As String)
        _apiKey = apiKey
    End Sub

    Public Async Function TranslateAsync(text As String,
                                   targetLang As String,
     Optional sourceLang As String = Nothing) As Task(Of String)

        System.Net.ServicePointManager.SecurityProtocol =
            System.Net.SecurityProtocolType.Tls12

        Dim url As String = "https://api-free.deepl.com/v2/translate"

        Dim content As New StringContent(
            BuildRequestBody(text, targetLang, sourceLang),
            Encoding.UTF8,
            "application/x-www-form-urlencoded"
        )

        Dim request As New HttpRequestMessage(HttpMethod.Post, url)
        request.Headers.Add("Authorization", $"DeepL-Auth-Key {_apiKey}")
        request.Content = content

        Dim response = Await _httpClient.SendAsync(request)
        response.EnsureSuccessStatusCode()

        Dim json As String = Await response.Content.ReadAsStringAsync()

        Using doc As JsonDocument = JsonDocument.Parse(json)
            Return doc.RootElement _
                      .GetProperty("translations")(0) _
                      .GetProperty("text") _
                      .GetString()
        End Using

    End Function

    Public Function Translate(text As String,
                              targetLang As String,
                              Optional sourceLang As String = Nothing) As String

        Return TranslateAsync(text, targetLang, sourceLang) _
            .GetAwaiter() _
            .GetResult()

    End Function

    Private Function BuildRequestBody(text As String,
                                     targetLang As String,
                                     sourceLang As String) As String

        Dim sb As New StringBuilder()

        sb.Append($"text={Uri.EscapeDataString(text)}")
        sb.Append($"⌖_lang={targetLang}")

        If Not String.IsNullOrEmpty(sourceLang) Then
            sb.Append($"&source_lang={sourceLang}")
        End If

        Return sb.ToString()

    End Function

End Class

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

public class DeepLClient
{
    private readonly HttpClient _httpClient;
    private string _apiKey;
    private bool apiKeySet = false;

    public DeepLClient()
    {
        _httpClient = new HttpClient();
    }

    public void SetAPIKey(string apiKey)
    {
        _apiKey = apiKey;
    }
    public async Task&ltstring> TranslateAsync(
        string text,
        string targetLang,
        string sourceLang = null)
    {
        System.Net.ServicePointManager.SecurityProtocol =
             System.Net.SecurityProtocolType.Tls12;

        var url = "https://api-free.deepl.com/v2/translate";

        var content = new StringContent(
            BuildRequestBody(text, targetLang, sourceLang),
            Encoding.UTF8,
            "application/x-www-form-urlencoded"
        );

        var request = new HttpRequestMessage(HttpMethod.Post, url);
        request.Headers.Add("Authorization",
            $"DeepL-Auth-Key {_apiKey}");
        request.Content = content;

        var response = await _httpClient.SendAsync(request);
        response.EnsureSuccessStatusCode();

        var json = await response.Content.ReadAsStringAsync();

        using (var doc = JsonDocument.Parse(json))
        {
            return doc.RootElement
                      .GetProperty("translations")[0]
                      .GetProperty("text")
                      .GetString();
        }
    }

    public string Translate(
        string text,
        string targetLang,
        string sourceLang = null)
    {
        return TranslateAsync(text, targetLang, sourceLang)
            .GetAwaiter()
            .GetResult();
    }

    private string BuildRequestBody(
        string text,
        string targetLang,
        string sourceLang)
    {
        var sb = new StringBuilder();
        sb.Append($"text={Uri.EscapeDataString(text)}");
        sb.Append($"⌖_lang={targetLang}");

        if (!string.IsNullOrEmpty(sourceLang))
        {
            sb.Append($"&source_lang={sourceLang}");
        }

        return sb.ToString();
    }
}