diff --git a/apps/preview/vite.config.ts b/apps/preview/vite.config.ts
index f4d5ea5..43b800c 100644
--- a/apps/preview/vite.config.ts
+++ b/apps/preview/vite.config.ts
@@ -4,7 +4,7 @@ import { defineConfig } from 'vite';
 
 export default defineConfig({
   plugins: [react()],
-  server: { port: 5174, strictPort: true },
+  server: { host: '127.0.0.1', port: 5174, strictPort: true },
   test: {
     environment: 'jsdom',
     include: ['src/**/*.test.{ts,tsx}'],
diff --git a/apps/studio/vite.config.ts b/apps/studio/vite.config.ts
index 3fa00c8..43a51c2 100644
--- a/apps/studio/vite.config.ts
+++ b/apps/studio/vite.config.ts
@@ -4,7 +4,7 @@ import { defineConfig } from 'vite';
 
 export default defineConfig({
   plugins: [react()],
-  server: { port: 5173, strictPort: true },
+  server: { host: '127.0.0.1', port: 5173, strictPort: true },
   test: {
     environment: 'jsdom',
     include: ['src/**/*.test.{ts,tsx}'],
diff --git a/docs/SETUP.md b/docs/SETUP.md
index 962c2b9..634d2b6 100644
--- a/docs/SETUP.md
+++ b/docs/SETUP.md
@@ -56,6 +56,7 @@ pnpm dev
 | Studio            | `http://localhost:5173` |
 | Preview           | `http://localhost:5174` |
 | Axis 65 demo site | `http://localhost:5175` |
+| Marketing site    | `http://localhost:5176` |
 
 Start only one workspace when needed:
 
@@ -63,6 +64,7 @@ Start only one workspace when needed:
 pnpm --filter @universal/studio dev
 pnpm --filter @universal/preview dev
 pnpm --filter @universal/demo-site dev
+pnpm --filter universal-marketing-site dev
 ```
 
 ## Windows PowerShell
@@ -116,10 +118,15 @@ Stop the process already using the port, or deliberately override the port for t
 pnpm --filter @universal/studio dev -- --port 6173
 pnpm --filter @universal/preview dev -- --port 6174
 pnpm --filter @universal/demo-site dev -- --port 6175
+pnpm --filter universal-marketing-site dev -- --port 6176
 ```
 
 Use the URL printed by Vite after an override. Any integration expecting the default Studio,
-Preview, or demo URL must be updated for that run.
+Preview, demo, or marketing-site URL must be updated for that run.
+
+All four dev servers bind `127.0.0.1` explicitly and use `strictPort`, so a collision fails loudly
+with `Port <n> is already in use` instead of one server silently serving on the port you expected
+another to use.
 
 On Windows, inspect a port without terminating anything:
 
diff --git a/examples/demo-site/vite.config.ts b/examples/demo-site/vite.config.ts
index a317e62..f8083a3 100644
--- a/examples/demo-site/vite.config.ts
+++ b/examples/demo-site/vite.config.ts
@@ -1,3 +1,6 @@
 import react from '@vitejs/plugin-react';
 import { defineConfig } from 'vite';
-export default defineConfig({ plugins: [react()], server: { port: 5175, strictPort: true } });
+export default defineConfig({
+  plugins: [react()],
+  server: { host: '127.0.0.1', port: 5175, strictPort: true }
+});
diff --git a/frontend/vite.config.ts b/frontend/vite.config.ts
index 56f7628..01090b6 100644
--- a/frontend/vite.config.ts
+++ b/frontend/vite.config.ts
@@ -1,4 +1,7 @@
 import { defineConfig } from 'vite';
 import react from '@vitejs/plugin-react';
 
-export default defineConfig({ plugins: [react()] });
+export default defineConfig({
+  plugins: [react()],
+  server: { host: '127.0.0.1', port: 5176, strictPort: true }
+});