diff --git a/src/core/index.js b/src/core/index.js
index 76a0d705..e5659065 100644
--- a/src/core/index.js
+++ b/src/core/index.js
@@ -47,6 +47,7 @@ module.exports = function SwaggerUI(opts) {
     showMutatedRequest: true,
     defaultModelRendering: "example",
     defaultModelExpandDepth: 1,
+    showExtensions: false,
 
     // Initial set of plugins ( TODO rename this, or refactor - we don't need presets _and_ plugins. Its just there for performance.
     // Instead, we can compile the first plugin ( it can be a collection of plugins ), then batch the rest.