Stable Local Dev URLs

STABILIZE. Replace random port numbers with named URLs. Agents and browser automation need deterministic, discoverable URLs — portless provides them. myapp.localhost:1355 instead of localhost:3247.

Rules

Always use named URLs (myapp.localhost:1355) in browser automation, tests, and documentation — never hardcode port numbers
Always integrate via package.json scripts — don't rely on manual portless <name> invocations
One name per service — names are the contract, ports are the implementation detail
URL format: http://<name>.localhost:1355 — port 1355 is always part of the URL unless overridden

When to Integrate

Signal	Action
New project with dev server	Add portless to `package.json` scripts
Multi-service project	Name each service: api, web, docs
Browser automation needed	Set up portless first for stable URLs
Port conflicts between projects	Give each project a unique name
CORS issues on localhost	`.localhost` domains share cookies predictably
Agent needs to find the app	Name it — `portless list` shows all active routes

Flow: Project Setup

One-time integration — after this, npm run dev always produces a stable URL.

npm install -g portless

Add to package.json:

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

First run auto-starts the proxy. Verify with portless list — should show myapp → localhost:<port>.

Open http://myapp.localhost:1355 — this URL never changes.

Flow: Multi-Service Naming

Convention: <service>.localhost:1355 for independent services, dotted names for subdomains.

{
  "scripts": {
    "dev:api": "portless api pnpm start",
    "dev:web": "portless web next dev",
    "dev:docs": "portless docs vitepress dev"
  }
}

Results in:

http://api.localhost:1355
http://web.localhost:1355
http://docs.localhost:1355

Dotted names create subdomains: portless api.myapp pnpm start → http://api.myapp.localhost:1355

Names are lowercased and validated: only [a-z0-9.-], no consecutive dots.

Flow: HTTPS Setup

When needed: OAuth callbacks, secure cookies, service workers.

portless proxy start --https
portless trust

After trust, https://myapp.localhost:1355 works without browser warnings. HTTP/2 is enabled automatically with HTTPS. One-time setup per machine.

Flow: Bypass

When you need to skip portless temporarily (debugging port issues, CI without proxy):

PORTLESS=0 npm run dev

Runs the command directly without proxy wrapping.

How It Works

Proxy on port 1355, random app port (4000-4999) via PORT env var, framework auto-detection injects --port and --host flags for frameworks that need them (Vite, Astro, Angular).

.localhost domains resolve to 127.0.0.1 natively — no /etc/hosts edits needed.

Stale routes auto-clean when the owning process PID dies. WebSocket proxying (HMR) works automatically.

Composition

With browser: agent-browser open "http://myapp.localhost:1355" — stable URL across all sessions and restarts
With watch: d3k wraps the dev command, portless wraps the name — portless myapp d3k -c "bun run dev" --no-tui --no-skills --no-agent for monitored development with stable URLs
With hope:loop: consistent URLs across wave iterations — port changes between restarts don't break automation
With agents: any agent can portless list to discover running services without knowing ports