Right now we only expose only one port to the external world. If you want to expose more than one service, you might try with a reverse proxy, like the one offered by the http-proxy npm package. That way, you might have different services listening at various port, and then the proxy listening at port 3000: the proxy might then convert different urls into different ports, for example:
https://your-project.glitch.me/serviceA/:path -> http://localhost:4000/:path
https://your-project.glitch.me/serviceB/:path -> http://localhost:5000/:path
https://your-project.glitch.me/serviceC/:path -> http://localhost:6000/:path