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Senior Ruby on Rails Developer

OnTheGoSystems

Posted 3 days ago

Senior Ruby on Rails Developer 

We are looking for a senior Ruby on Rails developer to help us build reliable, scalable products and apply AI/LLM technologies where they create real value.

This is a hands-on engineering role for someone who can own complex features end to end, make strong technical decisions, and work across backend architecture, production systems, testing, and AI-assisted product development.

You should be excited about AI, but pragmatic enough to know when a simple, deterministic solution is better than an LLM call.

What you’ll be working on:

  • Owning features from technical design to production
  • Building and maintaining Ruby on Rails systems used at scale
  • Designing AI/LLM-assisted features and workflows where they improve product quality or user experience
  • Working with LLM APIs, prompts, retrieval/context strategies, and AI-assisted development tools
  • Making trade-offs around performance, reliability, cost, latency, security, and maintainability
  • Writing and maintaining automated tests, including unit, integration, and E2E tests
  • Debugging production issues and improving system reliability

Requirements

What we’re looking for:

To succeed in this role, you’ll have:

  • Strong professional experience with Ruby on Rails, ideally at senior level
  • Experience building and running production systems used by real customers
  • Strong backend skills, including databases, API design, performance, background jobs, and security;
  • Ability to break down ambiguous problems and propose practical technical solutions
  • Hands-on interest or experience with AI/LLM technologies, 
  • Good judgment about when to use AI and when simpler engineering approaches are better
  • Strong testing habits and care for long-term code quality
  • A responsible, curious, flexible mindset: willing to debug, deploy, investigate, learn, and own outcomes

Nice to have: 

  • Experience with React
  • CI/CD, background jobs, or AWS experience
  • Experience building AI-powered product features in production
  • Familiarity with embeddings, vector search, RAG, evals, or LLM observability
  • Experience with text-processing, localization, translation, or multilingual products

Benefits

Why Join OTGS?

  • Stable & self-funded: Founded in 2007, profitable, and independent.
  • Industry leaders: Creators of WPML, the #1 multilingual plugin for WordPress, used on 1.

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Job details

Workplace

Hybrid

Location

Barcelona, Catalonia, Spain

Experience

SE

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