diff --git a/Runtime/Classes/SearchFilter.cs b/Runtime/Classes/SearchFilter.cs
index 054841a..9e50993 100644
--- a/Runtime/Classes/SearchFilter.cs
+++ b/Runtime/Classes/SearchFilter.cs
@@ -22,6 +22,7 @@ public class SearchFilter
         internal int pageSize;
         internal List<string> searchPhrases = new List<string>();
         internal List<string> tags = new List<string>();
+        internal List<string> excludedTags = new List<string>();
         internal List<long> users = new List<long>();
 #endregion
         /// <summary>
@@ -33,6 +34,11 @@ public void AddSearchPhrase(string phrase)
             searchPhrases.Add(phrase);
         }
 
+        public void ExcludeTag(string tag)
+        {
+            excludedTags.Add(tag);
+        }
+
         /// <summary>
         /// Adds a tag to be used in filtering mods for a request.
         /// </summary>
diff --git a/Runtime/ModIO.Implementation/Statics/FilterUtil.cs b/Runtime/ModIO.Implementation/Statics/FilterUtil.cs
index 7bb2b42..ec90956 100644
--- a/Runtime/ModIO.Implementation/Statics/FilterUtil.cs
+++ b/Runtime/ModIO.Implementation/Statics/FilterUtil.cs
@@ -43,6 +43,17 @@ public static string ConvertToURL(SearchFilter searchFilter)
                     url += $"&{Filtering.FullTextSearch}{phrase}";
                 }
             }
+
+            if(searchFilter.excludedTags != null && searchFilter.excludedTags.Count > 0)
+            {
+                url += "&tags-not-in=";
+                foreach(string tag in searchFilter.excludedTags)
+                {
+                    url += $"{tag},";
+                }
+                url = url.Trim(',');
+            }
+
             // add tags to filter
             if(searchFilter.tags.Count > 0)
             {