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A list of some baseline Rails interview questions
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Rails Interview Questions

I get a fair number of questions via Hacker Hours and elsewhere regarding what questions to use/expect in an interview for a Rails developer, so figured I would get it together in a tidy list. Pull requests welcome.



  • Personalize your list of questions.
  • Don't ask questions you don't know the answers to.
  • Mix trivia questions with open-ended ones.


  • Don't study to the test. Not all of these questions will be used, and others will be asked that aren't covered here. Know your stuff.
  • Rails skills != CS skills
  • Know whether you are interviewing for a full-stack vs. backend-focused position.
  • Have code up on Github/Bitbucket/wherever - the more side projects you have to talk about, the better.
  • Be comfortable with some version control system.

The Questions


  • What is a tree? What is a DAG?
  • Pseudo-code depth-first and breadth-first search.
  • Given a sorted array, what is the fastest way to find a element? What is the Big-O time to do so?


  • What is the difference between a lambda, a block and a proc? [I have gotten this one at every Ruby interview I've been in]
  • How do you sort an Array of objects by a particular attribute? What is a better way to do sorting with ActiveRecord?
  • What are some of your favorite gems? What are their alternatives?
  • In Ruby, which is generally the better option: a recursive function or an iterative one?
  • What are #method_missing and #send? Why are they useful?


  • What is the general history of Rails?
  • Explain the different pieces of Rails.
  • Walk through the flow of a request through Rails.
  • What are the different server options for running a Rails/Rack app?
  • Explain CSRF and how Rails combats it.
  • Explain mass-assignment vulnerability.


(no particular order)

Creative Commons License
Rails Interview Questions by Aidan Feldman is licensed under a Creative Commons Attribution 3.0 Unported License.

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