| Status | Interpretation | |--------|----------------| | Connection refused | No service listening on port 11501 | | 200 OK | Service running, response body shown | | 404 Not Found | Service up but wrong endpoint | | 403 Forbidden | Access denied | | Timeout / no response | Firewall or service stalled |

# Health check
http localhost:11501/health
python -m http.server 11502
http POST localhost:11501/users name="John Doe" age:=30

If port 11501 is occupied, you can often specify a different port when launching your application:
# Node.js example
PORT=11502 npm start
http PUT localhost:11501/users/1 name="Jane" age:=28

Your browser cannot magically create a service. You must start the application first.
On Windows (Command Prompt as Admin):
netstat -ano | findstr :11501

On macOS/Linux (Terminal):
lsof -i :11501

If nothing appears, no service is bound to that port.