setup-portless

Sets up Portless for a project to replace port numbers with stable named .localhost URLs. Use when configuring local development routing, fixing port conflicts, or setting up monorepo dev environments

SKILL.md

GitHub
<objective> Set up [Portless](https://github.com/vercel-labs/portless) for the current project. Portless replaces `localhost:PORT` with stable named URLs like `myapp.localhost:1355`, eliminating port conflicts, cookie collisions, and port-guessing issues for both developers and AI agents.

Requirements: Node.js 20+, macOS or Linux. </objective>

<quick_start> Run these commands to get started:
# Install globally
npm install -g portless

# Start the proxy daemon
portless proxy start

# Run your app with a named route
portless myapp next dev
# => http://myapp.localhost:1355
</quick_start> <process>

Step 1: Verify prerequisites

Check Node.js version is 20+ and platform is macOS or Linux:

node --version
uname -s

If Node.js < 20, inform the user they need to upgrade before proceeding.

Step 2: Detect project context

Read package.json to understand:

  • Project name (use as default app name)
  • Existing dev scripts (to know what command to wrap)
  • Whether this is a monorepo (look for workspaces field, or pnpm-workspace.yaml, turbo.json, lerna.json)
  • Framework in use (Next.js, Vite, Express, etc.) from dependencies

Step 3: Install Portless

npm install -g portless

Step 4: Choose app name(s)

Ask the user what name they want for their app URL. Suggest based on project name.

For monorepos, suggest subdomain naming:

  • api.projectname for backend
  • web.projectname or projectname for frontend
  • docs.projectname for documentation

Step 5: Update package.json scripts

Wrap the existing dev script with portless. For example, if the current script is:

{ "dev": "next dev" }

Update to:

{ "dev": "portless myapp next dev" }

For monorepos, update each workspace's package.json similarly.

Step 6: Verify setup

Run the dev script and confirm the app is accessible at the named URL:

npm run dev

The proxy auto-starts if not already running. Confirm output shows the .localhost:1355 URL.

Verify routes are registered:

portless list
</process> <common_patterns> <pattern name="single-app"> **Single application:**
{
  "scripts": {
    "dev": "portless myapp next dev"
  }
}

Access at: http://myapp.localhost:1355 </pattern>

<pattern name="monorepo"> **Monorepo with multiple services:**
# In packages/web/package.json
"dev": "portless web.myapp next dev"

# In packages/api/package.json
"dev": "portless api.myapp node server.js"

# In packages/docs/package.json
"dev": "portless docs.myapp next dev"

Access at:

  • http://web.myapp.localhost:1355
  • http://api.myapp.localhost:1355
  • http://docs.myapp.localhost:1355</pattern>
<pattern name="custom-proxy-port"> **Custom proxy port (e.g., port 80 for clean URLs):**
sudo portless proxy start -p 80
# Then: http://myapp.localhost (no port needed)
</pattern> </common_patterns> <environment_variables>
Variable Purpose Default
PORTLESS=0 or PORTLESS=skip Bypass portless, use default port (not set)
PORTLESS_PORT Override proxy port 1355
PORTLESS_STATE_DIR Custom state directory ~/.portless or /tmp/portless
</environment_variables> <cli_reference>
Command Purpose
portless <name> <cmd> [args...] Run app with named route
portless list Show active routes
portless proxy start Start daemon proxy on port 1355
portless proxy start -p <port> Start on custom port
portless proxy start --foreground Run in foreground (debugging)
portless proxy stop Stop the proxy daemon
</cli_reference> <anti_patterns> <pitfall name="forgetting-proxy"> The proxy auto-starts when you run `portless <name> <cmd>`, so there is no need to manually start it. Only use `portless proxy start` for custom port configuration. </pitfall> <pitfall name="windows"> Portless does not support Windows. Only set up on macOS or Linux. </pitfall> <pitfall name="old-node"> Portless requires Node.js 20+. Do not attempt installation on older versions. </pitfall> </anti_patterns> <success_criteria> Setup is complete when: - Portless is installed globally (`portless --version` succeeds) - Project `package.json` dev script(s) are wrapped with `portless <name>` - Running `npm run dev` (or equivalent) shows the app accessible at `<name>.localhost:1355` - For monorepos, each workspace has its own named route </success_criteria>