diff --git a/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/app/commands/check_nick/CheckUsernameHandler.java b/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/app/commands/check_nick/CheckUsernameHandler.java
new file mode 100644
index 0000000..d2c1d28
--- /dev/null
+++ b/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/app/commands/check_nick/CheckUsernameHandler.java
@@ -0,0 +1,29 @@
+package ch.unibas.dmi.dbis.cs108.casono.server.app.commands.check_nick;
+
+import ch.unibas.dmi.dbis.cs108.casono.server.domain.user.User;
+import ch.unibas.dmi.dbis.cs108.casono.server.domain.user.UserRegistry;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.command.execution.CommandHandler;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.protocol.response.dispatcher.ResponseDispatcher;
+import java.util.Optional;
+
+public class CheckUsernameHandler implements CommandHandler<CheckUsernameRequest> {
+    private final ResponseDispatcher responseDispatcher;
+    private final UserRegistry userRegistry;
+
+    public CheckUsernameHandler(ResponseDispatcher responseDispatcher, UserRegistry userRegistry) {
+        this.responseDispatcher = responseDispatcher;
+        this.userRegistry = userRegistry;
+    }
+
+    @Override
+    public void execute(CheckUsernameRequest request) {
+        Optional<User> user = userRegistry.getByUsername(request.getUsername());
+        UsernameAvailability availability;
+        if (user.isEmpty()) {
+            availability = UsernameAvailability.FREE;
+        } else {
+            availability = UsernameAvailability.TAKEN;
+        }
+        responseDispatcher.dispatch(new CheckUsernameResponse(request.getContext(), availability));
+    }
+}