Find and stop the dev servers your coding agent left running

Why they keep running

An agent runs commands such as npm run dev or tsc --watch through a shell. When the agent or its terminal closes, the shell goes away but its long-running child doesn't have to. macOS hands such a process to launchd, so its parent process ID (PPID) becomes 1. That orphaned process runs until you stop it or restart the Mac.

1. Dev servers still holding a port

lsof -nP -iTCP -sTCP:LISTEN

This lists every process of yours listening on a TCP port. Apps like your editor, Docker, or Spotify appear too; the leftovers are usually node, Python, ruby, bun, or deno on ports like 3000, 5173, 8000, or 8080. To stop one, see how to find and kill the process using a port.

2. Orphaned watchers and workers without a port

Watchers and queue workers don't listen on a port, so look for runtimes whose parent is gone:

ps -xo pid,ppid,etime,comm | awk 'NR==1 || ($2 == 1 && $4 ~ /(^|\/)(node|python[0-9.]*|Python|ruby|bun|deno)$/)'

ps -x includes your processes that have no terminal, comm is the executable path, and the awk filter keeps runtimes with PPID 1. The pattern matches the executable's whole name on purpose: a looser filter like /bun/ also matches system processes whose path contains .bundle.

ETIME is how long each one has been running. Not every match is a leftover: Homebrew services and other launch agents also run with PPID 1. Check brew services list before stopping something you set up on purpose.

3. See which project a process belongs to

ps -o pid,etime,command -p <PID>
lsof -a -d cwd -p <PID>

The full command shows what was run, and the working directory is usually the project it was started from. That is enough to tell the next dev from a closed task apart from one you are using right now.

4. Leave the agent's own tools alone

A running agent or editor also starts processes for itself: MCP servers, language servers, and file indexers. Stopping those breaks the session that is still open. Check the parent first:

ps -o ppid= -p <PID>              # prints the parent's PID
ps -o pid,command -p <PPID>

If the parent is the agent (claude, codex, a Cursor process) or your editor, and the process is not a dev server you asked for, leave it. It goes away when the agent exits. Processes with PPID 1 have no parent left, so they are safe to consider.

5. Stop the leftovers

pgrep -P <PID>     # list its child processes first
kill <PID>

kill sends SIGTERM so the process can shut down its own children. If pgrep -P still lists children a few seconds later, stop those by PID too. Use kill -9 only for a process that ignores SIGTERM.

Keeping it from happening

• Ask the agent to stop any server it started before it finishes, or to report the PIDs it left running.
• Start long-running dev servers in your own terminal and let the agent use them, instead of letting it launch its own.
• Check for leftovers when a port is unexpectedly busy or the Mac's fans spin up with nothing open.

DevPorts does these checks continuously in the menu bar. Its Background section lists orphaned and port-less dev processes, tags which agent or terminal started each one, and it never lists or stops the agents, editors, and terminals themselves.