Modern tooling watches for port conflicts. If you run npm start for a React app (usually port 3000), but port 3000 is busy, the dev server may cycle through open ports. If it reaches 11501 , it will launch there. Similarly, Vite, Next.js, and Angular CLI all have fallback mechanisms.

Using HTTPS locally on port 11501 serves several critical purposes:

Caddy automatically provisions real, trusted certificates from Let’s Encrypt for public domains, but it also supports local development with trusted local certs. Configure Caddyfile :

:

If it works, add an within your firewall settings to allow traffic on TCP Port 11501.

Ensure all internal scripts, stylesheets, and API fetch requests explicitly use the https:// protocol. Summary Best Practices

mkcert -install

const PORT = 11501; https.createServer(options, app).listen(PORT, () => console.log( Secure server running at https://localhost:$PORT ); );

In the modern world of web development, encountering a URL like https://localhost:11501 is becoming increasingly common. For the uninitiated, this string of characters—combining a secure protocol ( https ), a local hostname ( localhost ), and an unconventional port ( 11501 )—can look like a cryptic error message. For developers, however, it represents a critical frontier: the shift toward .

Then restart Nginx. Now https://localhost:11501 proxies to your HTTP app.

Even though localhost is exempted from some strict HTTPS rules (per RFC 6761), certain APIs still demand a valid certificate.

docker run -p 11501:443 my-app

(e.g., Node.js, Python, React, Docker, Laravel, .NET)

Since this is an https address, your browser may warn you that the connection is not private. This is common for local development.