Portless is a CLI tool that replaces numeric port numbers with named `.localhost` URLs for local development. Install it globally via npm, then prefix any dev command with `portless <name>` to get a stable URL like `https://myapp.localhost`. It runs a reverse proxy on port 1355, auto-assigns random ports to apps, and injects `--port`/`--host` flags for frameworks that ignore the `PORT` env variable. Features include HTTPS with auto-generated certs, subdomain organization for multiple services, automatic git worktree detection (each branch gets its own subdomain), and support for custom TLDs like `.test`.