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# Ruby on Rails Engineer

- **Company:** Onthegosystems España
- **Location:** Barcelona, Spain (Remote available)
- **Contract:** Permanent contract
- **Skills:** Artificial Intelligence, Amazon Web Services, Automation of Tests, Software Quality, Databases, Continuous Integration, Software Debugging, Software Architecture, Ruby on Rails, Search Technologies, ReactJS, Large Language Models, Reliability of Systems, Backend, Api Design
- **Published:** July 20, 2026
- **Apply:** https://www.adzuna.es/contact-us.html

## About the Role

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

## Description

We are looking for a Senior Ruby on Rails Engineer 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


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