diff --git a/examples/sync-server/index.js b/examples/sync-server/index.js
index 10286e479..1e1d31a48 100644
--- a/examples/sync-server/index.js
+++ b/examples/sync-server/index.js
@@ -5,8 +5,35 @@ import { WebSocketServer } from "ws"
 import { Repo } from "@automerge/automerge-repo"
 import { NodeWSServerAdapter } from "@automerge/automerge-repo-network-websocket"
 import { NodeFSStorageAdapter } from "@automerge/automerge-repo-storage-nodefs"
+import { default as Prometheus } from "prom-client"
 import os from "os"
 
+const registry = new Prometheus.Registry()
+Prometheus.collectDefaultMetrics({ register: registry })
+
+const buckets = Prometheus.linearBuckets(0, 1000, 60)
+
+const metrics = {
+  docLoaded: new Prometheus.Histogram({
+    name: "automerge_repo_doc_loaded_duration_millis",
+    help: "Duration of loading a document",
+    buckets,
+    registers: [registry],
+  }),
+  receiveSyncMessage: new Prometheus.Histogram({
+    name: "automerge_repo_receive_sync_message_duration_millis",
+    help: "Duration of receiving a sync message",
+    buckets,
+    registers: [registry],
+  }),
+  numOps: new Prometheus.Histogram({
+    name: "automerge_repo_num_ops",
+    help: "Number of operations in a document",
+    buckets: Prometheus.exponentialBuckets(1, 2, 20),
+    registers: [registry],
+  }),
+}
+
 export class Server {
   /** @type WebSocketServer */
   #socket
@@ -45,12 +72,25 @@ export class Server {
     }
     const serverRepo = new Repo(config)
 
+    // Observe metrics for prometheus and also log the events so log aggregators like loki can pick them up
+    serverRepo.on("doc-metrics", (event) => {
+      console.log(JSON.stringify(event))
+      metrics.numOps.observe(event.numOps)
+      if (event.type === "doc-loaded") {
+        metrics.docLoaded.observe(event.durationMillis)
+      } else if (event.type === "receive-sync-message") {
+        metrics.receiveSyncMessage.observe(event.durationMillis)
+      }
+    })
+
     app.get("/", (req, res) => {
       res.send(`👍 @automerge/example-sync-server is running`)
     })
 
-    app.get("/metrics", (req, res) => {
-      res.json(serverRepo.metrics())
+    // In a real server this endpoint would be authenticated or not event part of the same express app
+    app.get("/prometheus_metrics", async (req, res) => {
+      res.set("Content-Type", registry.contentType)
+      res.end(await registry.metrics())
     })
 
     this.#server = app.listen(PORT, () => {
diff --git a/examples/sync-server/package.json b/examples/sync-server/package.json
index e488c3ab2..b379f6296 100644
--- a/examples/sync-server/package.json
+++ b/examples/sync-server/package.json
@@ -15,6 +15,7 @@
     "@automerge/automerge-repo-network-websocket": "workspace:*",
     "@automerge/automerge-repo-storage-nodefs": "workspace:*",
     "express": "^4.18.1",
+    "prom-client": "^15.1.3",
     "ws": "^8.7.0"
   },
   "devDependencies": {
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 89a0d4c22..9c9da7efb 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -266,6 +266,9 @@ importers:
       express:
         specifier: ^4.18.1
         version: 4.19.2
+      prom-client:
+        specifier: ^15.1.3
+        version: 15.1.3
       ws:
         specifier: ^8.7.0
         version: 8.18.0
@@ -1027,6 +1030,10 @@ packages:
   '@octokit/types@9.3.2':
     resolution: {integrity: sha512-D4iHGTdAnEEVsB8fl95m1hiz7D5YiRdQ9b/OEb3BYRVwbLsGHcRVPz+u+BgRLNk0Q0/4iZCBqDN96j2XNxfXrA==}
 
+  '@opentelemetry/api@1.9.0':
+    resolution: {integrity: sha512-3giAOQvZiH5F9bMlMiv8+GSPMeqg0dbaeo58/0SlA9sxSqZhnUtxzX9/2FzyhS9sWQf5S0GJE0AKBrFqjpeYcg==}
+    engines: {node: '>=8.0.0'}
+
   '@pkgjs/parseargs@0.11.0':
     resolution: {integrity: sha512-+1VkjdD0QBLPodGrJUeqarH8VAIvQODIbwh9XpP5Syisf7YoQgsJKPNFoqqLQlu+VQ/tVSshMR6loPMn8U+dPg==}
     engines: {node: '>=14'}
@@ -1782,6 +1789,9 @@ packages:
     resolution: {integrity: sha512-Ceh+7ox5qe7LJuLHoY0feh3pHuUDHAcRUeyL2VYghZwfpkNIy/+8Ocg0a3UuSoYzavmylwuLWQOf3hl0jjMMIw==}
     engines: {node: '>=8'}
 
+  bintrees@1.0.2:
+    resolution: {integrity: sha512-VOMgTMwjAaUG580SXn3LacVgjurrbMme7ZZNYGSSV7mmtY6QQRh0Eg3pwIcntQ77DErK1L0NxkbetjcoXzVwKw==}
+
   bl@4.1.0:
     resolution: {integrity: sha512-1W07cM9gS6DcLperZfFSj+bWLtaPGSOHWhPiGzXmvVJbRLdG82sH/Kn8EtW1VqWVA54AKf2h5k5BbnIbwF3h6w==}
 
@@ -4244,6 +4254,10 @@ packages:
     resolution: {integrity: sha512-69agxLtnI8xBs9gUGqEnK26UfiexpHy+KUpBQWabiytQjnn5wFY8rklAi7GRfABIuPNnQ/ik48+LGLkYYJcy4A==}
     engines: {node: ^14.17.0 || ^16.13.0 || >=18.0.0}
 
+  prom-client@15.1.3:
+    resolution: {integrity: sha512-6ZiOBfCywsD4k1BN9IX0uZhF+tJkV8q8llP64G5Hajs4JOeVLPCwpPVcpXy3BwYiUGgyJzsJJQeOIv7+hDSq8g==}
+    engines: {node: ^16 || ^18 || >=20}
+
   promise-all-reject-late@1.0.1:
     resolution: {integrity: sha512-vuf0Lf0lOxyQREH7GDIOUMLS7kz+gs8i6B+Yi8dC68a2sychGrHTJYghMBD6k7eUcH0H5P73EckCA48xijWqXw==}
 
@@ -4924,6 +4938,9 @@ packages:
     resolution: {integrity: sha512-DZ4yORTwrbTj/7MZYq2w+/ZFdI6OZ/f9SFHR+71gIVUZhOQPHzVCLpvRnPgyaMpfWxxk/4ONva3GQSyNIKRv6A==}
     engines: {node: '>=10'}
 
+  tdigest@0.1.2:
+    resolution: {integrity: sha512-+G0LLgjjo9BZX2MfdvPfH+MKLCrxlXSYec5DaPYP1fe6Iyhf0/fSmJ0bFiZ1F8BT6cGXl2LpltQptzjXKWEkKA==}
+
   temp-dir@1.0.0:
     resolution: {integrity: sha512-xZFXEGbG7SNC3itwBzI3RYjq/cEhBkx2hJuKGIUOcEULmkQExXiHat2z/qkISYsuR+IKumhEfKKbV5qXmhICFQ==}
     engines: {node: '>=4'}
@@ -6283,6 +6300,8 @@ snapshots:
     dependencies:
       '@octokit/openapi-types': 18.1.1
 
+  '@opentelemetry/api@1.9.0': {}
+
   '@pkgjs/parseargs@0.11.0':
     optional: true
 
@@ -7109,6 +7128,8 @@ snapshots:
 
   binary-extensions@2.3.0: {}
 
+  bintrees@1.0.2: {}
+
   bl@4.1.0:
     dependencies:
       buffer: 5.7.1
@@ -9993,6 +10014,11 @@ snapshots:
 
   proggy@2.0.0: {}
 
+  prom-client@15.1.3:
+    dependencies:
+      '@opentelemetry/api': 1.9.0
+      tdigest: 0.1.2
+
   promise-all-reject-late@1.0.1: {}
 
   promise-call-limit@3.0.1: {}
@@ -10777,6 +10803,10 @@ snapshots:
       mkdirp: 1.0.4
       yallist: 4.0.0
 
+  tdigest@0.1.2:
+    dependencies:
+      bintrees: 1.0.2
+
   temp-dir@1.0.0: {}
 
   test-exclude@6.0.0: