diff --git a/README.md b/README.md
index 36a1cba..d8c1f31 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,8 @@
-To build, you'll need Docker. Run `./build.sh` and it should do the rest.
+To build, you'll need Docker. Then:
 
-Then, start a local HTTP server and navigate to `http://localhost:port/ui/`.
+```bash
+./build.sh # runs build in Docker for libapi.{mjs,wasm,worker.js}
+serve . # starts a local server with COOP/COEP
+```
+
+Then, navigate to http://localhost:5000/ui/ in Chrome.
diff --git a/serve.json b/serve.json
new file mode 100644
index 0000000..9046720
--- /dev/null
+++ b/serve.json
@@ -0,0 +1,17 @@
+{
+  "headers": [
+    {
+      "source": "**/*",
+      "headers": [
+        {
+          "key": "Cross-Origin-Embedder-Policy",
+          "value": "require-corp"
+        },
+        {
+          "key": "Cross-Origin-Opener-Policy",
+          "value": "same-origin"
+        }
+      ]
+    }
+  ]
+}