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What are my goto set of gems?

You’ve started using Rails and have discovered the power of including gems into your project. Now you wonder if there is a set of default gems that would help kickstart your next rails projects. Are there some things you do every time?

For me, I find it useful to have a standard template that sets up the common stuff I use.

Let’s start with the Gemfile:

source ''

gem 'rails'

gem 'bower-rails'
gem 'coffee-rails'
gem 'devise'
gem 'foundation-rails'
gem 'librato'
gem 'sass-rails'
gem 'slim-rails'

group :development do
  gem 'better_errors'
  gem 'binding_of_caller'
  gem 'heroku'
  gem 'parity'
  gem 'pry'

group :test do
  gem 'capybara-webkit'      
  gem 'rspec-rails'

gem ‘rails’

Pretty obvious right? Well, I usually will loosely tie this to a version after I’ve run bundle install for the first time. So that line ends up looking something like gem 'rails', '~> 4.1.2'.

gem ‘better_errors’

The default error message template in Rails improved a lot with the 4.1 release, however I find better_errors to be so much better.

When combined with gem 'binding_of_caller' things get really powerful.

As well as giving a nicer looking stack trace to point you towards the error, you also get a live console bound to the application as it was when the error was raised. This makes debugging so much nicer.

gem ‘bower-rails’

So often I see projects where dependency management has been thought about when it comes to Ruby but the JavaScript looks like the Wild West, with random libraries dumped into vendor/assets/javascripts.

Your Javascript deserves as much care and attention as your Ruby and this is where bower-rails comes in.

Bower is dependency management for Javascript.

This gem makes it easy to integrate it with your Rails app.

Just run rake bower:install.

Hopefully as part of your bootstrap script.

This will create a Bowerfile for you, which is a place to specify your dependencies in a format similar to your gems.

It will look something like this…

asset 'backbone'
asset 'moment'

Every time you make a change to your Bowerfile, you need to run rake bower:install to update the dependencies.


If you ran the Rails generator then the default Gemfile will include this.

It allows you to write your Javascript in Coffeescript instead and compile it (at runtime in development or as part of your deployment process in production).

If you’re using SASS and a templating language like HAML or Slim, then it makes sense to me to continue the whitespace significance in your Javascript.

Not familiar with Coffeescript? It’s the default flavour of Javascript in Rails and is a … that compiles into regular Javascript. Gives us some niceties like, ditching ;, {}, function, class to make dealing with prototypes simpler, and of course whitespace significance.

Just append your js files with to trigger the compilation in your asset pipeline.


This gem has emerged as the most used authentication solution in the Ruby community. Packaged as a Rails engine, it gives you a standard set of user sign in/out tools that are easily customisable.

You will save yourself a lot of time by using this.

At it’s most basic, you can have a user sign up/in system in less than 5 minutes:

bin/rails g devise:install
bin/rails g devise User
bin/rake db:migrate

Then add before_action :authenticate_user! to the controllers you want to protect and you’re done.


It’s good to have a framework for your HTML and CSS as well as your server side code. Foundation is a front-end framework from the team at Zurb and is a great alternative to Twitter Bootstrap.

This gem will insert the necessary files into your asset pipeline and get you up and with a CSS framework quickly.


The majority of apps I build initially get deployed to Heroku. It’s such an easy way to deliver your app.

The heroku gem gives command line access to Heroku which you can use to create new apps and manage existing ones, including things like provisioning add ons, setting environment variables and managing your databases.

It should save you a few trips to the Heroku dashboard.


Librato is an excellent service to gather stats on the performance of your app on Heroku.

By default these include measuring the performance of your dynos, the router and Postgres DB, but by following their convention for outputting data in your log files you can easily measure so much more.

Librato has a few keywords you can use to help track things, and probably the 2 most common ones are count and measure. Simply prefix whatever you want to track with these keywords and it gets picked up ready to be analysed.



count will just sum the values you give it, while measure gives you more statistical analysis options, such as the median, mean, standard deviation and much more.


Another of the Rails default gems. It enables SASS in the asset pipeline.

SASS is a pre-processor for CSS that introduces some useful features, such as nested rules for easier to read code, mixins that allow you to re-use common rules across your stylesheets without having to duplicate code, variables and basic data structures such as a map.

This is hugely useful in making your CSS more manageable and readable.


When it comes to writing my HTML templates I prefer to use a templating language with white space significance, most recently this has been Slim.

For me, this reads so much better than HTML, however YMMV with this as it’s quite a divisive topic.


A simple gem that will save you a lot of typing. This allows you to shorten your Heroku commands down to staging migrate instead of heroku run rake db:migrate -a my-heroku-app-name.


Essential piece of the toolkit. An irb session without pry feels clunky now.

pry is the missing REPL for Ruby. You want to deep dive into your code during a live IRB session, then this is for you. What about simply checking the source of a method before you run it? Yeah, you can do that too.


Writing tests first is a big deal for me, and rspec is my preferred tool.

This gem packages up all the pieces of Rspec that you’ll need to get started with.


I like to run some tests in a browser like environment, capybara-webkit does the job by giving you a headless version of webkit to run your tests in.


So there it is, my default Gemfile. I hope it’s useful to you and perhaps uncovers some useful tools for your next project.

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