Port3000— Next.js / development HTTP
The Next.js CLI defaults to port 3000. Other development servers may use it too, but Node.js and React themselves do not impose a universal listener port.
Registry assignments, software defaults and local listeners are different things. A port number alone does not identify or secure a service.
Configuration and troubleshooting
For Next.js, next dev --port 3002 --hostname 127.0.0.1 selects a local endpoint. When using an npm script, ensure arguments reach the underlying command.
Important limitations
3002 is an example, not a guaranteed free port. Do not expose a development server as a production service; update callbacks and proxy targets after changes.
Read-only checks: run on the server host
Choose the commands for your OS. Check TCP and UDP separately. No result is not a lasting availability guarantee; inspect host and container separately.
Linux
sudo ss -ltnp 'sport = :3000'macOS
sudo lsof -nP -iTCP:3000 -sTCP:LISTENWindows PowerShell
Get-NetTCPConnection -LocalPort 3000 -State ListenSources and review
Sources checked on:
This review covers the explanations and sources on this page, not your device or every community software entry below.
Software Using This Port (29 software)
Community software entries: links are references, not individual verification.
Node.js Development Server
Node.js is a runtime; the application chooses its listening port.
React Development Server
A React application uses the development port configured by its build tool or framework.
Usage Suggestions
- Before using port 3000, please confirm it is not occupied by other services
- If you encounter port conflicts, consider using other ports or stopping the occupying service
Frequently asked questions
What is port 3000 used for?
Port 3000 sits in the Development category. This page lists the registered purpose and the software commonly associated with it; to see what is actually listening on a specific machine, check the process with ss/netstat.
Is port 3000 TCP or UDP?
The registered protocol on this page is TCP. The same number behaves independently on each protocol: TCP may be listening while UDP is idle, so check them separately.
How do I check if port 3000 is in use?
On Linux: sudo ss -tlnp 'sport = :3000' for an exact port match. On macOS: sudo lsof -nP -iTCP:3000 -sTCP:LISTEN. On Windows PowerShell: Get-NetTCPConnection -LocalPort 3000 -State Listen. A listener counts as confirmed only when you can see the bind address and process name; without root/admin you will not see other users' processes.
Is port 3000 secure? Should I open it in my firewall?
A port number has no inherent security — it depends on whether the listening service is correctly configured and whether it needs exposure at all. Keep loopback/internal-only services firewalled; where public access is required, pair it with source restrictions, VPN or authentication. The caution section on this page lists port-specific risks.
Quick Info
- Port
- 3000
- Protocol
- TCP
- Categories
- Development
- Usage Status
- 29 software in use
Related Ports
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