diff --git a/src/main/java/tk/draganczuk/url/Routes.java b/src/main/java/tk/draganczuk/url/Routes.java
index 91a780b..f67de52 100644
--- a/src/main/java/tk/draganczuk/url/Routes.java
+++ b/src/main/java/tk/draganczuk/url/Routes.java
@@ -30,12 +30,15 @@ public class Routes {
 		}
 		String shortUrl = split[1];
 		shortUrl = shortUrl.toLowerCase();
+		
+		var shortUrlPresent = urlRepository
+				.findForShortUrl(shortUrl);
 
-		if (Utils.validate(shortUrl)) {
+		if (shortUrlPresent.isEmpty() && Utils.validate(shortUrl)) {
 			return urlRepository.addUrl(longUrl, shortUrl);
 		} else {
 			res.status(HttpStatus.BAD_REQUEST_400);
-			return "shortUrl not valid ([a-z0-9-_]+)";
+			return "shortUrl not valid or already in use";
 		}
 	}
 
diff --git a/src/main/resources/public/js/main.js b/src/main/resources/public/js/main.js
index c9a8190..312fd55 100644
--- a/src/main/resources/public/js/main.js
+++ b/src/main/resources/public/js/main.js
@@ -72,11 +72,22 @@ const submitForm = () => {
         method: "POST",
         body: `${longUrl.value};${shortUrl.value}`
     })
-        .then(_ => {
-            longUrl.value = "";
-            shortUrl.value = "";
+        .then((res) => {
+            if (!res.ok) {
+                controls = document.querySelector(".pure-controls");
+                errBox = document.createElement("p");
+                errBox.setAttribute("id", "errBox");
+                errBox.setAttribute("style", "color:red");
+                errBox.innerHTML = "Short URL not valid or already in use";
+                controls.appendChild(errBox);
+            }
+            else {
+                document.getElementById("errBox")?.remove();
+                longUrl.value = "";
+                shortUrl.value = "";
 
-            refreshData();
+                refreshData();
+            }
         });
 
 };