diff --git a/.changeset/short-doors-arrive.md b/.changeset/short-doors-arrive.md
new file mode 100644
index 000000000..5975720b0
--- /dev/null
+++ b/.changeset/short-doors-arrive.md
@@ -0,0 +1,5 @@
+---
+"@segment/analytics-core": minor
+---
+
+Allow custom property on CoreExtraContext Page
diff --git a/packages/core/src/events/interfaces.ts b/packages/core/src/events/interfaces.ts
index 0db091874..420273b63 100644
--- a/packages/core/src/events/interfaces.ts
+++ b/packages/core/src/events/interfaces.ts
@@ -117,6 +117,7 @@ export interface CoreExtraContext {
      * @example https://segment.com/academy/
      */
     url?: string
+    [key: string] : string
   }
 
   /**