diff --git a/replace.js b/replace.js
index e69de29..16ed1a8 100644
--- a/replace.js
+++ b/replace.js
@@ -0,0 +1,3 @@
+let header = document.createElement('h1');
+header.textContent = "Hello from the Replace Maps extension";
+document.body.insertBefore(header, document.body.firstChild);