PORT 8501 / TCPDev & LocalhostExposure Risk: Low
Port 8501: Streamlit Python AI Apps — Streamlit Data Science & AI Web App Server
Default local web server port when running `streamlit run app.py`.
Default Service
Streamlit Python AI Apps
Process: python (streamlit)
Transport Protocol
TCP
IANA Registered Port 8501
Docker Port Flag
-p 8501:8501
Container to Host Mapping
How to Check & Kill Process on Port 8501 (EADDRINUSE Fix)
macOS & Linux (lsof / kill)
# Find process using port 8501 sudo lsof -i :8501 # Instantly kill process on port 8501 lsof -ti:8501 | xargs kill -9
Windows (PowerShell & CMD)
# Find PID listening on port 8501 netstat -ano | findstr :8501 # Force kill by PID taskkill /PID <PID_NUMBER> /F
Cross-Platform Node.js One-Liner
# Kill port 8501 via npx npx kill-port 8501 # Or diagnose via Castov CLI npx castov fix "EADDRINUSE :::8501"
Linux Firewall (UFW) & Connectivity Test
# Test if port 8501 is reachable nc -zv localhost 8501 # Allow or deny port 8501 in UFW sudo ufw allow 8501/tcp
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Frequently Asked Questions about Port 8501
What is Port 8501 used for?
Port 8501 is the standard network port for Streamlit Python AI Apps (Streamlit Data Science & AI Web App Server) operating over TCP. The typical system daemon or process is python (streamlit).
How do I kill a process running on Port 8501 (EADDRINUSE)?
On macOS and Linux, run: lsof -ti:8501 | xargs kill -9 (or npx kill-port 8501). On Windows PowerShell/CMD, run: netstat -ano | findstr :8501 and then taskkill /PID <PID> /F.
Is it safe to expose Port 8501 to the internet?
Port 8501 has a Low security risk profile. Default local web server port when running `streamlit run app.py`.