Technical screening questions
Ask for one example per question and listen for specifics.
- How do you avoid N+1 queries in Rails? A good answer: includes or preload and detecting them with tools.
- What are Rails callbacks and when are they a problem? A good answer: Lifecycle hooks and hidden side effects.
- How do you run background jobs? A good answer: Sidekiq or ActiveJob with retries.
- How do you structure a large Rails app? A good answer: Service objects, concerns and boundaries.
- How do you upgrade Rails versions? A good answer: Deprecation warnings and stepwise upgrades.
Quick screening questions
Use these when you have only a few minutes.
- Which Rails version are you on and how did you upgrade?
- How do you find and fix N+1 queries?
- How do you structure background jobs?
What separates the levels
Match the level to the requirement before you submit.
- Junior: builds features with guidance.
- Mid: owns features and tests.
- Senior: leads architecture and upgrades.
Red flags
Any of these is a reason to probe further.
- Tutorial projects only.
- No test practice.
- Cannot discuss performance.
Tools you should hear mentioned
A Ruby on Rails developer with real experience usually names several of these without prompting.
- Ruby
- Ruby on Rails
- ActiveRecord
- RSpec
- Sidekiq
- PostgreSQL
Run the call well
Ask for the last project first, then dig into the second or third question. Take notes on versions, team size and outcomes, and record them with the submission so the vendor’s later technical interview does not surprise you.
Frequently asked questions
How long should a Ruby on Rails developer screening call take?
Fifteen to twenty minutes is enough to cover the project, three technical questions and availability, rate and work authorization.
Do recruiters need to know the technology?
Working vocabulary is enough. Use the sourcing guide for the role and listen for specifics instead of judging technical depth yourself.