HTTP Port 80

Localhost 80 Permission Denied?

Port 80 is a privileged port. You often need sudo or Admin rights to use it.

Try http://localhost →
Kill Port 80
sudo npx kill-port 80

Why can't I use Port 80?

On Unix-based systems (Mac/Linux), ports under 1024 are reserved. You must run your server with elevated privileges.

1. MacOS / Linux Fix

Prepend sudo to your start command.

sudo npm start
# or
sudo python -m http.server 80

2. Windows IIS Conflict

On Windows, the "World Wide Web Publishing Service" often hogs port 80. Stop it in services.msc.

net stop http

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