Caddyfile

{
    admin off
    log {
        output file /data/caddy.log
        format console
        level debug
    }
}

:3001 {
    handle /api/* {
        uri strip_prefix /api
        reverse_proxy localhost:3000
    }

    handle /api {
        rewrite * /api/
        reverse_proxy localhost:3000
    }
}