diff --git a/custom_metrics/event-names.js b/custom_metrics/event-names.js
new file mode 100644
index 00000000..707284fd
--- /dev/null
+++ b/custom_metrics/event-names.js
@@ -0,0 +1,9 @@
+const response_bodies = $WPT_BODIES;
+const eventNamePattern = /addEventListener\([\'"`](\w+)/g;
+
+return Object.fromEntries(response_bodies.filter(har => {
+  return eventNamePattern.test(har.response_body);
+}).map(har => {
+  const eventNames = Array.from(har.response_body.matchAll(eventNamePattern)).map(match => match[1]);
+  return [har.url, eventNames];
+}));
diff --git a/custom_metrics/initiators.js b/custom_metrics/initiators.js
new file mode 100644
index 00000000..d2a120ae
--- /dev/null
+++ b/custom_metrics/initiators.js
@@ -0,0 +1,11 @@
+const requests = $WPT_REQUESTS;
+return requests.reduce((map, request) => {
+  const url = request.url;
+  let initiator = request.initiator.url;
+  if (!initiator) {
+    initiator = request.initiator?.stack?.callFrames?.[0]?.url
+  }
+  map[initiator] = map[initiator] || [];
+  map[initiator].push(url);
+  return map;
+}, {});
diff --git a/custom_metrics/pwa.js b/custom_metrics/pwa.js
new file mode 100644
index 00000000..bdf779ce
--- /dev/null
+++ b/custom_metrics/pwa.js
@@ -0,0 +1,85 @@
+//[pwa]
+const response_bodies = $WPT_BODIES;
+const requests = $WPT_REQUESTS;
+const serviceWorkerRegistrationPattern = /navigator\.serviceWorker\.register\(['"]([^"']+)/m;
+
+const serviceWorkerURLs = response_bodies.filter(har => {
+  return serviceWorkerRegistrationPattern.test(har.response_body);
+}).map(har => {
+  const base = new URL(har.url).origin;
+  const serviceWorkerPath = har.response_body.match(serviceWorkerRegistrationPattern)[1];
+  return new URL(serviceWorkerPath, base).href;
+}).reduce((set, url) => {
+  set.add(url);
+  return set;
+}, new Set());
+
+
+const manifestURLs = new Set(Array.from(document.querySelectorAll('link[rel=manifest]')).map(link => {
+  const base = new URL(location.href).origin;
+  const href = link.getAttribute('href');
+  return new URL(href, base).href;
+}));
+
+
+const initiatorMap = requests.reduce((map, request) => {
+  const url = request.url;
+  let initiator = request.initiator.url;
+  if (!initiator) {
+    initiator = request.initiator?.stack?.callFrames?.[0]?.url
+  }
+  map[initiator] = map[initiator] || [];
+  map[initiator].push(url);
+  return map;
+}, {});
+
+function getURLsInitiatedBy(initialURL) {
+  let initiatorChain = [initialURL];
+  for (let i = 0; i < initiatorChain.length; i++) {
+    const url = initiatorChain[i];
+    if (url in initiatorMap) {
+      initiatorChain = initiatorChain.concat(initiatorMap[url].filter(url => {
+        return !initiatorChain.includes(url);
+      }));
+    }
+  }
+  return initiatorChain;
+}
+
+function getEntriesForURLs(urlSet) {
+  return response_bodies.filter(har => {
+    return urlSet.has(har.url);
+  }).map(har => {
+    return [har.url, har.response_body];
+  });
+}
+
+const serviceWorkers = getEntriesForURLs(serviceWorkerURLs);
+const manifests = getEntriesForURLs(manifestURLs).map(([url, body]) => {
+  let manifest;
+  try {
+    manifest = JSON.parse(body);
+  } catch (e) {
+    manifest = body;
+  }
+  return [url, manifest];
+});
+
+
+const serviceWorkerInitiatedURLs = new Set(Array.from(serviceWorkerURLs).flatMap(getURLsInitiatedBy));
+const serviceWorkerInitiated = getEntriesForURLs(serviceWorkerInitiatedURLs);
+
+const workboxPattern = /(?:workbox:[a-z\-]+:[\d.]+|workbox\.[a-zA-Z]+\.?[a-zA-Z]*)/g;
+// We should use serviceWorkerInitiatedURLs here, but SW detection has some false negatives.
+const workboxInfo = response_bodies.filter(har => {
+  return workboxPattern.test(har.response_body);
+}).map(har => {
+  return [har.url, Array.from(har.response_body.matchAll(workboxPattern)).map(m => m[0])];
+});
+
+return {
+  serviceWorkers: Object.fromEntries(serviceWorkers),
+  manifests: Object.fromEntries(manifests),
+  serviceWorkerInitiated: Object.keys(Object.fromEntries(serviceWorkerInitiated)),
+  workboxInfo: Object.fromEntries(workboxInfo)
+};