diff --git a/main/src/main/java/org/mobilitydata/gtfsvalidator/report/model/FeatureMetadata.java b/main/src/main/java/org/mobilitydata/gtfsvalidator/report/model/FeatureMetadata.java
index 47721e8f76..dc190746f2 100644
--- a/main/src/main/java/org/mobilitydata/gtfsvalidator/report/model/FeatureMetadata.java
+++ b/main/src/main/java/org/mobilitydata/gtfsvalidator/report/model/FeatureMetadata.java
@@ -16,6 +16,10 @@ public String getFeatureName() {
     return featureName;
   }
 
+  public String getFeatureGroup() {
+    return featureGroup;
+  }
+
   public String getDocUrl() {
     String formattedFeatureName = featureName.toLowerCase().replace(' ', '-');
     String formattedFeatureGroup = featureGroup.toLowerCase().replace(' ', '_');
diff --git a/main/src/main/java/org/mobilitydata/gtfsvalidator/report/model/FeedMetadata.java b/main/src/main/java/org/mobilitydata/gtfsvalidator/report/model/FeedMetadata.java
index 7ed9ecaa31..45df2f3152 100644
--- a/main/src/main/java/org/mobilitydata/gtfsvalidator/report/model/FeedMetadata.java
+++ b/main/src/main/java/org/mobilitydata/gtfsvalidator/report/model/FeedMetadata.java
@@ -590,4 +590,13 @@ public void setFilenames(ImmutableSortedSet<String> filenames) {
   public ImmutableSortedSet<String> getFilenames() {
     return filenames;
   }
+
+  public Boolean hasFlexFeatures() {
+    return specFeatures.keySet().stream()
+        .anyMatch(
+            feature ->
+                feature.getFeatureGroup() != null
+                    && feature.getFeatureGroup().equals("Flexible Services")
+                    && specFeatures.get(feature));
+  }
 }
diff --git a/main/src/main/resources/report.html b/main/src/main/resources/report.html
index 48430b4da4..1db8f42bed 100644
--- a/main/src/main/resources/report.html
+++ b/main/src/main/resources/report.html
@@ -221,6 +221,14 @@
         align-content: center;
         flex-wrap: wrap;
     }
+
+    .warning-display {
+        padding: 10px;
+        border: solid 2px orange;
+        border-radius: 11px;
+        width: fit-content;
+        font-weight: bold;
+    }
 </style>
 
 </head>
@@ -239,6 +247,11 @@ <h1>GTFS Schedule Validation Report</h1>
 
     <p>Use this report alongside our <a href="https://gtfs-validator.mobilitydata.org/rules.html">documentation</a>.</p>
 
+    <p class="warning-display" th:if="${metadata.hasFlexFeatures}">
+        &#9888; This feed contains GTFS Flex features. Please note that GTFS Flex validation support is still in development.
+        You can manually review all the validation rules for Flex data <a href="https://docs.google.com/document/d/1QABoIeOdR6lAB7A6_X6WIbZwC7EnAIZvm_hRNwNQeoI/edit#heading=h.mky28yjwt08z">here</a>.
+    </p>
+
     <p class="version-update" th:if="${summary.newVersionOfValidatorAvailable}">A new version of the <a
             href="https://github.com/MobilityData/gtfs-validator/releases">Canonical GTFS Schedule validator</a> is available!
         Please update to get the latest/best validation results.</p>