diff --git a/public/sw.js b/public/sw.js
new file mode 100644
index 00000000..9bae1f62
--- /dev/null
+++ b/public/sw.js
@@ -0,0 +1,15 @@
+// Retires the service worker the old Gatsby site installed in visitors' browsers.
+// Safe to delete once old registrations have had months to expire.
+self.addEventListener("install", () => self.skipWaiting());
+
+self.addEventListener("activate", (event) => {
+  event.waitUntil(
+    (async () => {
+      for (const key of await caches.keys()) await caches.delete(key);
+      await self.registration.unregister();
+      for (const client of await self.clients.matchAll({ type: "window" })) {
+        client.navigate(client.url);
+      }
+    })(),
+  );
+});