Your Local Dev Setup Is Outdated (Here's Why)

5 services running. Which port is which? Named localhost URLs. AI agents that actually work. Monorepo routing in two commands. Here's everything portless does. And why you need it. Right now, you probably have 3 or 4 services running locally. Maybe 5. Frontend. API server. Admin panel. Auth service. Webhook proxy. Then it happens. That error. Address already in use. Which process is hogging the port? Kill it, retry. By the time you fix it, you've completely lost your train of thought.

Every developer has been here. More than once. But here's what nobody actually talks about. Your AI coding assistant has the same problem. When Cursor or Cloud Code writes a fetch call, it guesses the port. And half the time, it's wrong. The API is on 3001. The agent hardcoded 3000. Test fails. Config breaks. You think the AI is being dumb. Really? Your local environment gave it nothing to work with. This isn't an AI problem. It's an environment problem. Your production app. api.myapp.com. Clear. Readable. Memorable.

Your local app. localhost colon 3001. A meaningless number. Port numbers made sense in the 90s. You ran one server, one port. Now you run 5 services simultaneously. And we're still using digits. The fix isn't a smarter AI. It's a smarter environment. That fix is portless. An open-source tool from Versal Labs. One command. You wrap your normal dev command with portless, give your app a name, and it appears at the name.localhost URL.

myapp.localhost. Port 1355. Instead of 5 port numbers you'll forget by morning, you get 5 names you'll never forget. web.myapp.localhost. api.myapp.localhost. admin.myapp.localhost. auth.myapp.localhost. hooks.myapp.localhost. All running simultaneously. All routed automatically. No config files, no port conflicts. Ever. The magic is in how portless handles ports behind the scenes.

When you run a service through portless, it automatically assigns a random port in the 4000 range. You never know what that port is, and you don't need to. The proxy maps your name to that port. Every time. Same URL every session, and if you ever need to bypass portless for any reason, set portless to 0, 0 login. For monorepos, this is a game-changer. Imagine your stack. A Next.js frontend, an Express API, an admin panel, an auth service. With regular ports, you need to remember and document four different numbers.

Change one? Update your cores config, your OAuth redirect URIs, your entire team's documentation. With portless, each service gets a subdomain. web.myapp for the frontend. api.myapp for the backend. admin.myapp for the admin panel. One base URL pattern, forever stable. Now back to that AI agent problem. When your agent knows your app lives at api.myapp.localhost, it writes the correct URL. Every time. No guessing. No wrong ports.

Portless even ships an agents.md file. Explicit instructions for AI coding assistance. It's one of the only developer tools built with AI agents as first-class users from day one. Stable URLs mean reliable agents. It's that simple. There's one more problem ports create that nobody thinks about until it bites them. Cookies. Set a cookie on localhost 3000. It can bleed across to 3001. Sources there, auth tokens, session data, colliding between your services.

With portless, each service is a real subdomain. Cookies are fully isolated. No more mysterious auth bugs at 2 in the morning. Portless is from Versal Labs, the experimental team behind Next.js. It's open source, Apache 2.0 licensed, free forever. And it works with every major framework. Next.js, Feed, Express, Remix, Nuxt, anything that respects the port environment variable. Which is basically everything. To get started, npm install "-g portless".