# How to find what is using port 3000 on a Mac > Open the NotchStar Disk tab, Monitor, Ports, then filter by 3000 to see the command, project folder and whether it is local or on the network. Canonical: https://www.notchstar.com/use-cases/find-what-is-using-port-3000-on-a-mac/ Last updated: 2026-11-04 Published 2026-11-04. Open the notch, choose Disk, then Monitor, and switch to Ports. Type 3000 in the filter. If something is listening there, you see its project folder, its command line and its working directory. You can open it in a browser, show the folder in Finder or ask it to quit, without writing an lsof command. ## Steps 1. Open the notch and choose **Disk**. 2. Choose the **Monitor** section, then press **Ports**. The other view is Usage. 3. The count at the top reads like "5 listening, 3 local". 4. Type the port in the filter field, for example 3000. It matches the port number, process, project, command and working directory, so you can also type a project name. 5. Read the row. It shows the port in bold, the project name, the command line (for example the dev server script), and the folder path with your home folder shortened to a tilde. 6. The tag on the right says **local** if the address is only reachable from this Mac, or **network** in orange if other machines can reach it. ## What you can do from the row - **Open in browser** goes to `http://localhost` and the port. - **Show project in Finder** reveals the working directory. It is disabled when no folder is known. - **Stop** asks the process to quit. See [stopping a dev server](https://www.notchstar.com/use-cases/stop-a-dev-server-from-the-mac-notch/) for how that works. ## How it gets the data NotchStar reads the system's own lsof and ps. The Ports list refreshes about every nine seconds while the Monitor section is on screen, and sampling stops when you leave. It does not run in the background. ## Limits - **TCP listeners only.** UDP sockets and outgoing connections are not listed. - **Your processes are the ones you can stop.** macOS refuses to let you stop other users' processes, and NotchStar does not ask for extra privileges. - **The project name is a guess.** It is the nearest folder above the working directory that looks like a project, or the directory itself. - **A process started in a container** may show as the container runtime rather than your server. - **It is not a firewall or a security scanner.** The network tag tells you the listening address, not whether a firewall blocks access. - **Sample lag.** A server that started a moment ago may take a refresh to appear. If the Ports list is empty, the filter may be hiding everything, or nothing is listening. The tab says "No port matches" or "Nothing is listening on a port." Pair this with [the CPU view](https://www.notchstar.com/use-cases/see-which-process-is-using-the-cpu-on-a-mac/) when the port is held by something busy. The [Disk page](https://www.notchstar.com/features/disk/) lists the other seven sections. ## Quick answers. ### What does the Ports list show? TCP listeners found with lsof: the port, the project folder, the command, the working directory and whether it is local only or open to the network. ### Does it show UDP ports or connections? No. It lists TCP listeners only. ## Keep reading. - [Disk space, duplicates, apps and cleanup](https://www.notchstar.com/features/disk/): See free space, find big folders, duplicates and app leftovers, compress media and clean caches from your Mac notch. Everything goes to the Trash. - [How to stop a dev server that is still running on a Mac](https://www.notchstar.com/use-cases/stop-a-dev-server-from-the-mac-notch/): Use NotchStar Disk, Monitor, Ports to find a forgotten dev server and press Stop twice to send a quit request. It never forces a kill. - [How to see which process is using the most CPU or memory on a Mac](https://www.notchstar.com/use-cases/see-which-process-is-using-the-cpu-on-a-mac/): The NotchStar Disk tab, Monitor, Usage shows the five busiest processes by CPU and by memory, refreshed every few seconds. No per app history. - [CPU, memory, disk, battery and network](https://www.notchstar.com/features/system-stats/): Live CPU, memory, disk, battery and network speed gauges in your Mac notch. Sampling only runs while the tab is open, so it stays light. ## More in Coding. - [How to stop a dev server that is still running on a Mac](https://www.notchstar.com/use-cases/stop-a-dev-server-from-the-mac-notch/): Use NotchStar Disk, Monitor, Ports to find a forgotten dev server and press Stop twice to send a quit request. It never forces a kill. - [How to see which process is using the most CPU or memory on a Mac](https://www.notchstar.com/use-cases/see-which-process-is-using-the-cpu-on-a-mac/): The NotchStar Disk tab, Monitor, Usage shows the five busiest processes by CPU and by memory, refreshed every few seconds. No per app history. - [How to reuse terminal commands from clipboard history on a Mac](https://www.notchstar.com/use-cases/copy-commands-from-clipboard-history-on-a-mac/): Copy several commands while reading docs, then paste them one at a time from the NotchStar Clipboard tab. Plain text, 50 items, cleared on quit. - [How to free up disk space on a Mac used for development](https://www.notchstar.com/use-cases/free-up-disk-space-on-a-developer-mac/): Scan caches, logs, Xcode DerivedData and old downloads with the NotchStar Disk tab, choose what to move to the Trash, and learn what each item means. - [How to watch CPU and memory while a build runs on a Mac](https://www.notchstar.com/use-cases/watch-cpu-and-memory-during-a-build-on-a-mac/): Keep the NotchStar System tab open while a build or test run goes, then check Disk, Monitor for the heaviest processes. Totals only, no history.