https://developer.mozilla.org/en-US/docs/Web/Security/Secure...
So you don't need self signed certs for HTTPS on local if you want to, for example, have a backend API and a frontend SPA running at the same time talking to eachother on your machine (authentication for example requires a secure context if doing OAuth2).
Won't `localhost:3000` and `localhost:3001` also both be secure contexts? Just starting a random vite project, which opens `locahost:3000`, `window.isSecureContext` returns true.
Usually you'd have a reverse proxy running on port 80 that forwards traffic to the appropoiate service, and an entry in /etc/hosts for each domain, or a catch all in dnsmasq.
Example: a docker compose setup using traefik as a reverse proxy can have all internal services running on the same port (eg. 3000) but have a different domain. The reverse proxy will then forward traffic based on Host. As long as the host is set up properly, you could have any number of backends and frontends started like this, via docker compose scaling, or by starting the services of another project. Ports won't conflict with eachother as they're only exposed internally.
Now, wether you have a use for such a setup or not is up to you.