diff --git a/app/src/main/java/eu/faircode/email/DeepL.java b/app/src/main/java/eu/faircode/email/DeepL.java
index a9b8221317..1836f708b1 100644
--- a/app/src/main/java/eu/faircode/email/DeepL.java
+++ b/app/src/main/java/eu/faircode/email/DeepL.java
@@ -37,8 +37,13 @@ import java.nio.charset.StandardCharsets;
 import javax.net.ssl.HttpsURLConnection;
 
 public class DeepL {
+    // https://www.deepl.com/docs-api/
     private static final int DEEPL_TIMEOUT = 20; // seconds
 
+    // curl https://api-free.deepl.com/v2/languages \
+    //	-d auth_key=42c191db-21ba-9b96-2464-47a9a5e81b4a:fx \
+    //	-d type=target
+
     public static String translate(String text, String target, Context context) throws IOException, JSONException {
         String request =
                 "text=" + URLEncoder.encode(text, StandardCharsets.UTF_8.name()) +