I would recommend looking into uWSGI. I have only used it a little but found it to be far more stable and performant than all the current Perl application server backends and as full-featured as any. It’s got a PSGI compatibility layer that you’ll need to include when you build it and run apps under it. Any of the new gen frameworks will work out of the box with it (need config and proxy/port strategy and probably want a static server in front—I recommend nginx though I guess you’ve already made your choice there). Any older stuff, even CGI, could be adapted pretty easily with PSGI/Plack shims and middleware.