Pow 0.4.3

Zero-configuration Rack server for Mac OS X
Pow is a zero-configuration Rack server for Mac OS X and it will make developing Rack and Rails apps as frictionless as possible. You can install Pow in ten seconds and have your first app up and running in under a minute.

No mucking around with /etc/hosts, no compiling Apache modules, no editing configuration files or installing preference panes. And running multiple apps with multiple versions of Ruby is trivial.

How does it work? A few simple conventions eliminate the need for tedious configuration. Pow runs as your user on an unprivileged port, and includes both an HTTP and a DNS server.

The installation process sets up a firewall rule to forward incoming requests on port 80 to Pow. It also sets up a system hook so that all DNS queries for a special top-level domain (.dev) resolve to your local machine.


To serve a Rack app, just symlink it into your ~/.pow directory. Let's say you're working on an app that lives in ~/Projects/myapp. You'd like to access it at http://myapp.dev/.

Setting it up is as easy as:

cd ~/.pow
ln -s ~/Projects/myapp

That's it! The name of the symlink (myapp) determines the hostname you use (myapp.dev) to access the application it points to (~/Projects/myapp).


Pow requires Mac OS X version 10.6 or newer. To install or upgrade Pow, just open a terminal and run this command:

curl get.pow.cx | sh

You can review the install script yourself before running it, if you'd like.

The firewall rule installed by Pow redirects all incoming traffic on port 80 to port 20559, where Pow runs. This means if you have another web server running on port 80, like the Apache that comes with Mac OS X, it will be inaccessible without either disabling the firewall rule or updating that server's configuration to listen on another port.


If you decide Pow's not for you, uninstallation is just as easy:

curl get.pow.cx/uninstall.sh | sh

Further information on how to use Pow on your Mac is available HERE.

Main features:

  • Convention trumps configuration:
  • Don’t let tedious configuration get in the way of building great apps. With Pow, there are no preference panes to install. No Apache configuration files to update. And Pow eliminates the need to edit /etc/hosts. To get a Rack app running, just type a single command.
  • No maintenance required:
  • Pow is a clean, self-contained server that runs as your user without root privileges. There are no Apache extensions to compile, no gems to install. A single command installs and upgrades Pow automatically. And your system files are left pristine and untouched.
  • Tame multiple Rubies:
  • With full support for rvm and Bundler, Pow makes it simple to run multiple apps at once, each with its own version of Ruby and its own set of gems. Testing your apps on different runtimes—like JRuby and Rubinius—has never been easier. And gem activation errors are a thing of the past.

last updated on:
April 6th, 2014, 10:39 GMT
file size:
60 KB
license type:
MIT License 
developed by:
Sam Stephenson
operating system(s):
Mac OS X 10.6 or later
binary format:
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What's New in This Release:
  • Upgrade Nack to 0.16 to fix issues when requiring the json library.
read full changelog

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