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Hire our Elite Ruby on Rails Developers

FullStack Labs is a leading team of Ruby on Rails developers, engineers, programmers, coders, and architects. Uber, Siemens, and hundreds of other companies have chosen us for their mission critical software development projects.

Hire Our Elite ruby on rails Developers Now
What's included

We’ll review your code base and provide a report that includes quality scores for the following:

  • Test suite and test coverage
  • Code quality, including a CodeClimate report
  • How soon can FullStack start on my project?
  • Dependencies
  • Error and performance monitoring
  • Documentation
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Trusted By:
UberSiemensEricssonNFIBEkso BionicsCalifornia

Some of our expert Ruby on Rails Developers.

By combining USA and Canada technical leads and project managers with Senior Developers in Latin America, we offer clients the quality, security, and convenience of onshore development paired with the cost savings of nearshore development.
Roberto Sawamura
Senior Software Engineer
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Latin America
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 Years of Experience

Senior Software Engineer, Roberto Sawamura, Latin America

Shawn Cheng
Software Architect
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 Years of Experience

FullStack Labs, Senior Software Engineer‍

Pablo Cordero
Software Architect
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Latin America
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Senior Software Engineer, Ruby on Rails Developer

Ben Carle
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 Years of Experience

As the CIO of FullStack Labs I'm directly responsible for managing and contributing to our most critical client projects. I'm a senior software engineer with 15 years of experience building complex custom software and leading development teams.

Christian Suárez
Senior Software Engineer
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Latin America
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 Years of Experience

As a Senior Software Engineer, I have a passion for computers and technology. I believe there's a lot of value in the data that we generate on our apps and computers that could help to discover insights useful for solving a large number of society's problems.

Douglas Lise
Senior Software Engineer
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Latin America
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 Years of Experience

I have been working with software development for over 15 years. Initially, I worked with desktop software, then with mobile apps. In the last eight years, I've been a full-stack web developer with a heavier focus on the back end.

Roger Vaca
Senior Software Engineer
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Latin America
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 Years of Experience

Senior Software Engineer, Roger Vaca, Latin America

Moises Narvaez
Software Architect
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Latin America
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 Years of Experience

As a Senior Software Engineer at FullStack Labs I'm primarily focused on custom development using Ruby on Rails and other.

Why Developers Love Ruby on Rails

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Ruby on Rails allows us to quickly develop prototypes that can later be built out into full production apps, which reduces costs early on, and speeds up time to market.

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Ruby on Rails has a huge following in the open source community, is supported by both large companies and individual contributors, and has a plethora of well maintained open source gems.

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Ruby on Rails prioritizes convention over configuration, which makes Rails developers happy while keeping the system simple enough to maintain complex applications.

Client Testimonials

The experience I've had with other firms is in direct contrast to what FullStack did. I'm comparing them with two other firms I worked with in the past. They care a lot about what their clients are doing. They bring their ideas and concepts to the table. I felt like they were on my team. They added a lot of value in terms of ideas and continue to do so. No matter who's working on the project you feel like they care about the work that's being produced.

- Rob Burns -
President, Bunk 1

FullStack Labs' managers have been engaged throughout. The whole project management staffing, matching team to task has been fantastic. All their staff is very committed. I'm very aware of how much bureaucracy there is in the tech world, and we've gotten nothing but solutions. I am totally happy with their approach to everything, their integrity, honesty, the whole thing. It's great.

- Executive Director -
Valley CAN

We were very happy with the way the whole process was facilitated. We started talking to FullStack Labs three months before we signed any contract with them. We met with them in person several times. We wanted to find out what their philosophy is. Both Brian and David are fathers with young children, so they understand the importance of the work we are doing. That shows through in their work. It was obvious they cared deeply.

- Anna Sadovnikova -
CEO, MomKit

How to Hire Ruby on Rails Developers Through FullStack Labs

  • 1. Talk to us!

    We will work with you to understand your technical needs, team dynamics, and goals.

  • 2. Meet our available talent

    We’ll send you FullStack Ruby on Rails developers that match your technical requirements, with links to their FullStack profile page which outlines their work experience and technical abilities, as well as their FullStack technical summary page, which includes a 60 minute video of the developer completing FullStack’s coding challenge, and a plethora of other technical information from their interview with us.

  • 3. 14 Day Risk-free trial

    Start the engagement. Work with your new Ruby on Rails developers for a trial period, ensuring they're the right fit.

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Engagement Models for Ruby on Rails Projects

New Ruby on Rails Apps

We design and build greenfield apps of all shapes and sizes using Ruby on Rails.

Existing Ruby on Rails Apps

Have a legacy Ruby on Rails app? We’re here to help. From debugging and maintenance to feature development and DevOps, we'll tailor a development plan to meet your needs.

Ruby on Rails Team Augmentation

Need to add a Ruby on Rails developer to your existing team? We'll seamlessly integrate as many Rails developers as needed, to help you go faster and level up your team's skills.

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FullStack Labs is proudly remote.

We have an ever growing team of incredible people currently located in these countries.
Meet our Leadership Team
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Meet our Leadership Team

Our Clients Love Us, And You Will Too.

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Let's Talk!

We’d love to learn more about your project.
Engagements start at $75,000.


Essential Technical Ruby On Rails Interview Questions

FullStack Labs is a leading team of Ruby on Rails developers, engineers, programmers, coders, and architects. Uber, Siemens, and hundreds of other companies have chosen us for their mission-critical software development projects. Ruby on Rails is a crucial tool to develop your project, here are a few Ruby on Rails Interview Questions you can use to screen your Ruby on Rails candidates:

Q: Please describe what polymorphic associations are in Rails and give an example of a scenario in which they should be used.


Polymorphic associations allow a model to connect to multiple other models, imagine a scenario where you have two models, Employee and Product and you need to allow each one of those to have a picture image, without using polymorphic associations, you may be using two different models (EmployeePicture and ProductPicture) and tables (employee_pictures and product_pictures), by using polymorphic associations, you only need a single table to store the pictures since they can belong to more than one other model.

Q: Describe what inheritance, encapsulation, and polymorphism are in Rails, and provide an example for each.


Inheritance allows the programmer to inherit the characteristics of one class into another class. Ruby supports only single class inheritance, it does not support multiple class inheritance but it supports mixins.

class Mammal  
  def breathe  
	puts "inhale and exhale"  
class Cat < Mammal  
  def speak  
	puts "Meow"  
	cat = Cat.new
	cat.breathe # => “inhale and exhale”
	cat.speak # => “Meow”

Encapsulation means that the internal representation of an object is hidden from the outside. Only the object can interact with its internal data. Public methods can be created to open a defined way to access the logic inside an object.

class Document
  attr_accessor :name

  def initialize(name)
    @name = name

  def set_name(name)
    @name = name
d = Document.new('name1')

Polymorphism is the provision of a single interface to entities of different types.

class Document
  def initialize

  def print
	raise NotImplementedError, 'You must implement the print method'

class XmlDocument < Document
  def print
	p 'Print from XmlDocument'

class HtmlDocument < Document
  def print
	p 'Print from HtmlDocument'

XmDocument.new.print # Print from XmlDocument
HtmlDocument.new.print # Print from HtmlDocument
Q: What is the difference between a module and a class in Ruby?


They may look similar, both can hold method definitions or constants, but there are some differences:

  • you can instantiate objects from a class, but you cannot do it from a module
  • you can create subclasses from a class, but you cannot create submodules from a module
  • Modules are intended to be included on classes
Q: What is the difference between 'include ModuleName' and 'extends ModuleName?' How can class methods and variables be used when 'extended' versus 'included'? Please provide an example(s).


include ModuleName is used to append methods from the module as instance methods of the class, while extend ModuleName is used to append methods as class methods. When using include the methods can be accessed directly from the instance

my = MyClass.new

When using extends, the methods can be accessed from the class itself, like:

Q: What are the benefits of, or scenarios in which, you would use ActiveSupport::Concern in Rails?


ActiveSupport::Concern provides a simpler way to create modules that can be included/shared in other classes, it also handles constant dependencies automatically. One pretty common scenario for concerns is extracting pieces of code that can be shared between different models.

Q: What is the difference between a Block, Proc and Lambda?


Procs are objects, so we can create objects from a Proc and treat them as any other class instance. Lambdas are a kind of Proc that validates its parameters, procs do not validate them, however both can be used to create a block and store it in a variable to later pass it to a method. Blocks are like anonymous functions that can be passed into methods, they are called when using the yield keyword in a method definition.

Q: What is the purpose of HashWithIndifferentAccess class into ActiveSupport?


Implements a hash where keys :foo and "foo" are considered to be the same. Internally symbols are mapped to strings when used as keys in the entire writing interface (calling []=, merge, etc).

Q: Describe at least two Ruby hook methods and explain when they are called.



  • respond_to_missing?: a way to make sure your dynamic methods defined with method_missing also handle respond_to? correctly
  • method_missing: called when a method cannot be found, potentially to allow dynamically defining one instead
  • method_added: called whenever a method is added… which can be used to modify the method
  • method_removed: called whenever a method is removed
  • singleton_method_added: method added to the singleton class of the object, to be callable just on this one instance
  • singleton_method_removed: method removed from singleton class
  • method_undefined: a method has been undefined, with undef_method. Undef_method is different from remove_method because remove_method may still allow superclasses to define the method – undef_method means it’s gone entirely.
  • singleton_method_undefined: called when a singleton method is undefined entirely
  • initialize_copy: an optional callback when cloning any Object


  • inherited: a Ruby class is subclassed


  • append_features: a Module is included, and its constants, methods and variables used
  • included: a Module is included, which usually obsoletes “append_features”
  • extend_object: a Module extends an Object
  • extended: an Object is extended by a module, which mostly obsoletes extend_object
  • const_missing: a constant isn’t already present
Q: Describe what Rails does on the client, and the format of the url that gets called, when `remote: :true` is added to a link.


Rails using its UJS library listens for click events to links with the data-remote=true set, then it captures it preventing the default behaviour of the browser, then calling it via an AJAX request. The format of the URL usually ends in .js, ie, /users.js.

Q: What should be the response from the server for `remote: :true` call?


Usually, response from the server for a remote call is javascript response, this means that the browser will evaluate the content of the response with Javascript, in Rails the response comes from a view partial with extension .js.erb allowing the evaluation of Ruby code inside before the Javascript code is sent back to the browser.

Q: What's the use of the db/seed.rb file? How do you handle multiple seed files?


Seeds file is used as a mechanism of populating the database with test or default data. Handling multiple seeds files requires them to be manually loaded in the db/seeds.rb file

Q: What's the relative path inside of the project directory to a controller called Admin::ManagersController?



Q: What is the difference between ActiveRecord and AREL?


ActiveRecord is a high-level interface to construct SQL queries using Ruby and associate the result from database to ActiveRecord models (when possible), ActiveRecord queries are translated to SQL when sending to the database, it is simple and easy to learn and use, but it has limitations when it comes to complex SQL queries. Arel on the other side is the library used under the hood by ActiveRecord to construct the SQL queries, both of them allow you to build SQL queries using Ruby, but Arel is more flexible, it allows to dynamically compose SQL queries using a Ruby interface, it is strong and well designed.

Q: What ORM or query interface would you most want to use other than Active Record?


Sequel, pretty powerful and flexible

Q: Who is your favorite Rubyist and why?


This answer is based on opinion, focus on the why. Example, Aaron Patterson, he is working hard on improving the performance of Ruby towards the Ruby 3x3 (version 3 will be 3 times faster) goal.

Q: What are your top three sources for Ruby / Rails news and content?


This answer is based on opinion. Official Rails Blog, the Slack Ruby Community, and the Ruby subreddit.