[bryanlarsen]

I this is quite similar to Rails; by default Rails includes webbrick or puma.

[shmerl]

OK, browsing through their code, I see they use Hyper.

[Tobu]

But they're still on the previous, non-Tokio release.

Personally I'm more tempted by something like Susanoo: https://github.com/ubnt-intrepid/susanoo/