Tech hiring Software engineering
Hire Ruby on Rails developers who know the conventions.
A Ruby on Rails developer builds and maintains web applications on the Rails framework, from the data model through to the screens and the background jobs. Rails rewards people who follow its conventions and know when to step outside them, and that judgement is what we assess before a developer reaches your shortlist.
01 The role
What a Ruby on Rails developer does, and what they ship.
A Rails developer works across the whole application. In one pull request they may add a migration, a model with its validations, a controller, the view, a background job and the tests for all of it. The framework is designed for that breadth, which is why a small Rails team can carry a product that would need several specialists on another stack.
Starting a Rails application is the easy part. Living with one for eight years is harder. Callbacks trigger other callbacks, models grow to a thousand lines, a page fires hundreds of queries because an association was loaded lazily, and a major version upgrade keeps being postponed. Experienced Rails developers are valued mainly for keeping a mature monolith fast, comprehensible and current.
Recent Rails has moved back towards the server. Hotwire, meaning Turbo and Stimulus, delivers responsive interfaces without a separate JavaScript application, and Rails 8 can run jobs, caching and WebSockets from the database with the Solid libraries and deploy with Kamal. A good developer knows these defaults, and also knows Sidekiq, Redis and a React front end, because most existing codebases use them.
What they ship
- SaaS products and marketplaces, from sign-up to subscription billing
- Server-rendered interfaces made interactive with Turbo and Stimulus
- JSON APIs for mobile apps and separate front ends
- Background jobs on Sidekiq or Solid Queue: emails, imports, webhooks
- Admin and back-office tools for operations and support teams
- Rails and Ruby version upgrades on long-lived applications
- Test suites in RSpec or Minitest that make refactoring safe
02 Skills and stack
What Ruby on Rails developers work with, and what is optional.
Rails versions and front-end approach vary a lot between codebases. Tell us your Rails version, whether the interface is Hotwire or a JavaScript framework, and whether you test with RSpec or Minitest.
Core
The role cannot be done without these.
- Ruby: blocks, modules, the object model
- Rails conventions across the whole framework
- Active Record, migrations and SQL
- Testing with RSpec or Minitest
- Background jobs and idempotency
- HTML, CSS and server-rendered views
- Web security in Rails
- Refactoring a mature codebase
Tooling
Varies from team to team.
- Rails 7 and 8
- PostgreSQL
- Hotwire: Turbo and Stimulus
- Sidekiq with Redis, or Solid Queue
- RSpec or Minitest, with Capybara and FactoryBot
- RuboCop and Brakeman
- Bundler
- Kamal, Heroku, Render or Fly.io
- Devise or Rails’ built-in authentication
- ViewComponent
Adjacent
Useful, not required.
- React or Vue, for codebases with a JavaScript front end
- Stripe and other payment integrations
- Docker and CI/CD
- Search (Elasticsearch, Meilisearch, pg_search)
- Application monitoring (AppSignal, Datadog, Sentry)
- Sorbet or RBS type checking
03 When to hire one
Signs you need a Ruby on Rails developer, and signs you need someone else.
We would sooner point you to a different role than fill the wrong one. Both lists are worth a minute.
Hire a Ruby on Rails developer when
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Your product is a Rails application
It sounds obvious, but a capable developer from another stack takes months to absorb Rails conventions. Someone who already has them is productive in the first sprint.
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You are several Rails versions behind
An upgrade across major versions touches gems, configuration, deprecations and the test suite. People who have done it know to go one version at a time, and how to keep shipping features meanwhile.
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A small team has to ship a whole product
Rails gives two or three developers accounts, billing, an admin, email and jobs without assembling a stack. It suits an early company that must move quickly with few people.
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The application has slowed as the data grew
Pages that were fine with a thousand records time out at a million. This is usually queries, indexes and memory, and an experienced Rails developer knows where to look.
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The original Rails developers have left
The code works and nobody on the team fully understands it. You need someone who can read an unfamiliar Rails codebase and take ownership without proposing a rewrite.
Look elsewhere when
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You are starting fresh and need to hire many developers quickly
The Rails talent pool is smaller than the JavaScript one in every market. If headcount will grow fast, a more widely known stack is easier to staff.
Hire Node.js developers -
The core of the product is data science or machine learning
Ruby has little of that ecosystem. Rails can sit in front, but the modelling work belongs in Python.
Hire Python developers -
The interface is a complex client-side application
Hotwire covers most business screens. A design tool, an editor or an offline-capable app needs a dedicated front-end engineer working against a Rails API.
Hire React developers -
The work is generic and the stack is not yet chosen
If you have no Rails code, do not narrow the search to it by default. Brief the problem and consider full-stack developers across stacks.
Hire full-stack developers -
Deployments and infrastructure are what keep failing
Rails developers can deploy an application, but a fragile pipeline or cluster is a job for an infrastructure specialist.
Hire DevOps engineers
04 How we assess
Four stages, before a Ruby on Rails developer reaches your shortlist.
A CV says what someone claims. We test what they can do, then send you the evidence with the shortlist.
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Stage 1
Profile review
We look for Rails applications the candidate has worked on over time, not only tutorials: the version, the size of the codebase, the testing approach and their own part in it. Where code is public, we read models, tests and migrations for how closely they follow the framework.
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Stage 2
Technical test
A timed test on Ruby fundamentals, Rails conventions, Active Record and SQL, with coding exercises and a problem-solving task. We look at whether the Ruby is idiomatic and whether the candidate reaches for what the framework already provides.
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Stage 3
Conversation with our team
Our engineers ask the candidate to walk through a Rails application they maintained: where the business logic lived, how they kept queries under control, how jobs were made safe to retry, and what an upgrade involved. We ask what they would not do the Rails way, and why.
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Stage 4
Review and levelling
Reviewers score accuracy, speed, problem-solving, communication and teamwork, then assign a level from our engineering framework. For Rails roles the notes record which Rails versions the person has used in production and whether their experience is of new builds, long-lived applications or both.
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Then
Your shortlist
Assessed candidates, with notes and scores.
The engine
Evalia
Assessments run on Evalia, the assessment platform we built ourselves. Across the ProDevs network, more than 100,000 assessments have been completed.
The levels we assign are public. Read the engineering framework, or see how a hire runs from brief to offer.
05 Seniority
Three levels. What each one can own.
The title on a CV tells you little. What matters is how much a Ruby on Rails developer can be handed without someone checking each step.
Junior
Owns a resource, start to finish
- Adds a model, controller, views and tests by following the conventions already in place
- Writes migrations that are safe to run and to roll back
- Uses associations and scopes correctly, and asks before adding a callback
- Needs guidance on performance, job design and larger refactors
Mid-level
Owns a feature area of the monolith
- Ships features that span models, jobs, mailers and Turbo-driven views
- Finds N+1 queries and missing indexes with the logs and a profiler
- Extracts logic from oversized models and controllers without changing behaviour
- Changes large tables with migrations that do not lock production
Senior
Owns the application’s long-term health
- Leads Rails and Ruby upgrades and keeps the gem list short and current
- Draws boundaries inside the monolith and decides when, if ever, to extract a service
- Keeps the test suite fast and trustworthy enough that people run it
- Tunes memory, concurrency and the job system for the load the business has
06 Interview questions
Questions for Ruby on Rails developers, and what to listen for.
Borrow these for your own interview loop. Beside each is what to listen for.
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How do you detect and fix N+1 queries in a Rails application?
A good answer shows: They read the development log or use Bullet or strict loading, then fix with includes or preload and know the difference from eager_load. Strong candidates mention when a hand-written query or a counter cache is the better answer.
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When do you use an Active Record callback, and when do you avoid one?
A good answer shows: Caution. Callbacks suit small, local concerns such as normalising a field. Sending emails or calling an API from one produces surprises in tests, imports and the console. A candidate who puts all business logic in callbacks has not maintained a large application.
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Describe a Rails upgrade you did. What was the plan?
A good answer shows: One version at a time, deprecation warnings cleared first, gems checked for compatibility, perhaps dual-booting in CI, and new framework defaults enabled gradually. If they have not done one, a sensible plan described honestly is acceptable at mid-level.
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How would you add a NOT NULL column with a default to a table with 50 million rows?
A good answer shows: Awareness that a naive migration can lock the table. They talk about adding the column, backfilling in batches, then adding the constraint, and know how their database version behaves. Tools such as strong_migrations are a good sign.
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A Sidekiq or Solid Queue job runs twice. How do you make sure that is harmless?
A good answer shows: Jobs take record identifiers, not serialised objects, check state before acting, and use unique constraints or locks where it matters. They understand at-least-once delivery and do not assume the queue guarantees more.
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When is Hotwire enough, and when would you reach for React?
A good answer shows: Hotwire for forms, lists, navigation and live updates driven by the server; a JavaScript framework for heavy client-side state or offline use. The best answers describe something built both ways and what each cost to maintain.
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A model has grown to 1,500 lines. What do you do about it?
A good answer shows: They identify distinct responsibilities and extract them into plain Ruby objects, concerns used sparingly, or separate models, with tests in place first. They resist both leaving it alone and introducing an elaborate architecture overnight.
07 Ways to engage
Four ways to bring a Ruby on Rails developer in.
A permanent hire is the usual route, not the only one. Choose by how long the work lasts and who should employ the person.
- Placement fee, of first-year salary. One-time.
- 10–15%
- Replacement guarantee on direct hires.
- 2 weeks
- To a first shortlist, for most roles.
- 48h
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Direct hire
A permanent employee on your contract and your payroll. One-time placement fee of 10–15% of first-year salary.
Tech hiring -
Dedicated team
A Ruby on Rails developer inside a team we assemble and run for you: product, design and engineering on your roadmap, for a monthly retainer.
Dedicated teams -
Outsourcing & payroll
A full-time person in a country where you have no legal entity. ProDevs employs and pays them: 20% of salary if we find the person for you, or 5% of salary, capped at $500 a month, for payroll and compliance on someone you have already chosen.
Outsourcing -
Freelance project
A defined piece of work with a clear end. You pay the agreed price per milestone through escrow, plus a 5% client fee. Free to post.
Freelancers
08 Around the role
Who Ruby on Rails developers depend on, and who depends on them.
Rails teams are usually small, and each developer covers a lot of ground: database, server, interface and often deployment. A Rails developer therefore works directly with product and design more than a back-end specialist would, and has fewer colleagues to hand things to.
- Product manager
- Turns a requirement into a small, shippable change, often the same week, and says what the convention already gives for free.
- Product designer
- Builds the screens themselves, so agrees early which interactions are cheap in Turbo and which are not.
- Front-end or mobile developer
- Provides and versions the JSON API when the product has clients beyond the Rails views.
- DevOps engineer
- Shares responsibility for deploys, job workers, database migrations and memory use in production.
- Support and operations staff
- Maintains the admin tools they rely on and investigates customer issues from the console.
09 Client testimonials
Hear it first-hand, from companies that hired.
Founders, operators and executives describe working with ProDevs, in their own words.
Play video: Client testimonial: Olufemi Seyi, COO, Casafina development company
Play video: Client testimonial: Aproko Doctor, Building AwaDoc
Play video: Client testimonial: JT Liddell, Promenade CEO
10 Questions
Hiring Ruby on Rails developers, answered.
Something else? Book a call (opens in a new tab) and ask us directly.
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Is Ruby on Rails still a good choice in 2026?
For a web product built by a small team, yes. The framework is actively developed, well documented and productive, and many established SaaS companies run on it. Its limits are a smaller hiring pool than JavaScript or Python and a thin ecosystem for data science. If you already have a Rails application, keeping it current is almost always better than rewriting it.
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Are Rails developers harder to find than other developers?
There are fewer of them than JavaScript or Python developers in any market, and they tend to be experienced, since few people now learn Rails as a first framework. Searching a wider region helps. Be precise in the brief about version, testing framework and front-end approach so the shortlist is small and accurate.
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Can a Rails developer handle the front end as well?
Usually. Rails developers write HTML, CSS and server-rendered views as part of the job, and Hotwire lets them add live updates and partial page changes without a separate JavaScript application. If your interface is a React or Vue app talking to a Rails API, ask for that experience or pair them with a front-end specialist.
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We have an old Rails application. Should we upgrade or rewrite?
Upgrade, in nearly every case. A rewrite discards years of fixes for edge cases nobody remembers, and takes longer than planned. An incremental upgrade, one Rails version at a time with the test suite as a safety net, keeps the product shipping. Look for a senior developer who can describe a previous upgrade in detail.
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How do you assess Rails developers?
In four stages. We review the Rails applications a candidate has worked on, set a timed technical test covering Ruby, Rails conventions and SQL, hold a conversation with our engineering team about a codebase they maintained, and then review the results together to assign an engineering level. The assessments run on Evalia, our own platform.
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How long does it take to hire a Rails developer through ProDevs?
For most roles you see a first shortlist within 48 hours of agreeing the brief, and most companies find their hire within two to three weeks. A direct hire carries a one-time placement fee of 10–15% of first-year salary and a two-week replacement guarantee.
Talk to ProDevs
Tell us about the role.
Tell us the level and the stack. We will tell you how quickly we can put assessed Ruby on Rails developers in front of you.
Project work
Need it for a project instead?
Not every job needs a full-time hire. Describe the work, get proposals from vetted freelance Ruby on Rails developers, and pay per milestone through escrow. Free to post.