# Fix "address already in use" for wrangler dev

Find and stop whatever is using port 8787, 9229, 4321 or 5173, with commands for macOS, Linux and Windows, and how to stop leftover workerd processes.

- Enter the port from the error message and get the commands to find the process (lsof on macOS and Linux) and stop it.
- Shows how to run wrangler dev on a different port (--port, --inspector-port).
- Includes commands to find and kill leftover workerd processes.
- Lists the common default ports: 8787 (wrangler dev), 9229 (inspector), 4321 (Astro), 5173 (Vite).

- Page: https://workerdock.app/tools/port-in-use-fixer/
- Free, no sign-up. Runs in the browser; nothing you enter is sent to a server.
- From the makers of WorkerDock (https://workerdock.app/), a free Mac app for local Cloudflare Workers projects.