diff --git a/src/main/java/org/gcube/nlphub/NLPUploader.java b/src/main/java/org/gcube/nlphub/NLPUploader.java
index 6e32c78..9f89a11 100644
--- a/src/main/java/org/gcube/nlphub/NLPUploader.java
+++ b/src/main/java/org/gcube/nlphub/NLPUploader.java
@@ -81,8 +81,8 @@ public class NLPUploader extends HttpServlet {
 	private void handleFreeText(HttpServletRequest request, HttpServletResponse response)
 			throws ServletException, IOException {
 		String freeText = request.getParameter("freetext");
-		freeText = freeText.replaceAll("[\\s]+", " ").trim();
-
+		freeText = NlpUtils.replaceDirtyCharacters(freeText);
+		
 		byte[] content = freeText.getBytes("UTF-8");
 		String fileName = generateFileName();
 		PrintWriter writer = response.getWriter();
@@ -132,8 +132,8 @@ public class NLPUploader extends HttpServlet {
 				bufferedContent = buffer;
 
 			String stringContent = new String(bufferedContent);
-			stringContent = stringContent.replaceAll("[\\s]+", " ").trim();
-			
+			stringContent = NlpUtils.replaceDirtyCharacters(stringContent);
+
 			ws.deleteFile(fileName, token);
 
 			if (!ws.uploadFile(stringContent.getBytes(), fileName, Constants.DEFAULT_DESCRIPTION, token)) {
diff --git a/src/main/java/org/gcube/nlphub/nlp/NlpUtils.java b/src/main/java/org/gcube/nlphub/nlp/NlpUtils.java
index 0c1ea3b..5e8ee6e 100644
--- a/src/main/java/org/gcube/nlphub/nlp/NlpUtils.java
+++ b/src/main/java/org/gcube/nlphub/nlp/NlpUtils.java
@@ -44,7 +44,21 @@ public class NlpUtils {
 		return content;
 	}
 	
-
+	public static String replaceDirtyCharacters(String source) {
+		
+		char c = 0;
+		for (int i = 0; i < source.length(); i++) {
+			c = source.charAt(i);
+			if (!((c >= 33 && c <= 90) || (c >= 97 && c <= 122) || (c >= 128 && c <= 167) || (c >= 180 && c <= 183) || (c >= 210 && c <= 212) || (c >= 214 && c <= 216) || (c >= 224 && c<=255))) {
+				source = source.replace(source.substring(i, i + 1), " ");
+			}
+		}
+		
+		source = source.replaceAll("[\\s]+", " ").trim();
+		source = source.replaceAll("<", " ").trim();
+		source = source.replaceAll(">", " ").trim();
+		return source;
+	}
 	
 	/*
 	public static void main(String[] args) {