We’ve just released version 0.4.0 of Pow, our zero-configuration web server for Rails development on OS X.

There are several new features in this release, including port proxying and better support for zsh users, but my favorite is a tiny addition that makes a huge difference when testing your apps on mobile devices.

Pow has always made it easy to access Rails apps on your computer with its built-in .dev domain. Just symlink your app into the ~/.pow directory and visit http://myapp.dev/ in your browser.

But what about testing your apps on mobile devices, or in IE? Pow’s .dev domain only works on your local machine.

Until now, testing on other computers required modifying /etc/hosts or setting up a custom DNS server on your router. Now we’ve fixed that, too.

Introducing xip.io, the magic domain name

Pow 0.4.0 has built-in support for xip.io, a free service from 37signals that provides wildcard DNS for any IP address.

With xip.io you can access your Rails apps from devices on your local network, like iPads, iPhones, Windows VMs, and other computers. No configuration required.

Say your development computer’s LAN IP address is With the new version of Pow, you can now access your app at http://myapp. And xip.io supports wildcard DNS, so any and all subdomains of resolve too.

Read more about xip.io at http://xip.io/ or check out the full source code on GitHub.

Installing and upgrading

See the full 0.4.0 release notes and install or upgrade with one simple command from your terminal:

curl get.pow.cx | sh

As always, the user’s manual and annotated source code are available for your perusal.