Port Number Reference

A port number identifies a specific service on a computer. When you access http://localhost:3000, the 3000 is the port. Click any port for what runs on it, how to check if it's in use, and how to open or block it.

Web Servers & Protocols

PortServiceNotes
80
HTTP
Default web — Apache, Nginx, IIS
›
443
HTTPS
Encrypted HTTP — SSL/TLS
›
8080
HTTP Alternate
Tomcat, Jenkins, Spring Boot, proxy
›
8443
HTTPS Alternate
Tomcat HTTPS, UniFi controller
›
21
FTP
File Transfer Protocol — legacy, prefer SFTP
›
22
SSH / SFTP
Secure shell and secure file transfer
›
25
SMTP
Outgoing email — blocked on most home ISPs
›
53
DNS
Domain name resolution — UDP and TCP
›

Development Frameworks

PortFramework / ToolNotes
3000
React, Next.js, Express, Node
Most popular dev server port
›
3001
Create React App, Storybook
Used when 3000 is already taken
›
5173
Vite (Vue, Svelte, React)
Modern frontend dev server
›
4200
Angular CLI
Angular development server default
›
8000
Django, FastAPI, Python HTTP
Python web framework default
›
5000
Flask, .NET Kestrel
Python Flask dev default
›
8888
Jupyter Notebook / JupyterLab
Data science notebook environment
›
4000
Jekyll, Rails dev, Ember
Ruby static site generator default
›
4848
GlassFish Admin Console
Java EE application server
›

Databases

PortDatabaseConnection string
3306
MySQL / MariaDB
mysql -h 127.0.0.1 -P 3306
›
5432
PostgreSQL
psql -h localhost -p 5432
›
6379
Redis
redis-cli -p 6379
›
27017
MongoDB
mongosh --port 27017
›
1433
Microsoft SQL Server
sqlcmd -S localhost,1433
›
9200
Elasticsearch
curl localhost:9200
›

Self-Hosted & Home Lab

PortApplicationNotes
8123
Home Assistant
Smart home automation platform
›
32400
Plex Media Server
Access at /web after the port
›
8096
Jellyfin
Open-source Plex alternative
›
9000
Portainer
Docker container management UI
›
9090
Prometheus
Metrics collection & alerting
›
3000
Grafana
Monitoring dashboards (shares port with dev)
›
1883
MQTT (Mosquitto)
IoT messaging protocol
›

Network & Remote Access

PortServiceNotes
3389
RDP — Windows Remote Desktop
Remote control Windows PCs
›
5900
VNC
Remote desktop — Display :0 = port 5900
›
51820
WireGuard VPN
Modern fast VPN protocol — UDP
›
2375
Docker Daemon (unencrypted)
Never expose this to the internet
›
5774
Splunk Web
Log analysis platform
›
1745
Puppet Agent
Configuration management
›
11501
Various Enterprise Apps
Check your application docs
›

How to Check If a Port Is in Use

# Windows
netstat -aon | findstr :3000

# macOS / Linux
lsof -i :3000
# or
ss -tulnp | grep 3000

How to Open a Port (Port Forwarding)

To make a local service accessible from the internet, forward the port on your router. See the port forwarding guide for step-by-step instructions for all major router brands.