Full Stack Developer - Ruby on Rails, REST API, TDD, Postgres, React & Next.JS

Full Stack Developer - Ruby on Rails, REST API, TDD, Postgres, React & Next.JS. 80% REMOTE (1 DAY PER WEEK IN OFFICE - LONDON)

About the Role

We are looking for an experienced Contract Full Stack Developer with deep expertise in Ruby on Rails to join our engineering team. This is a backend-focused role (approximately 75% Ruby on Rails / 25% Postgres, API, REST API, TDD, React & Next.js) where you'll play a key role in designing, building and maintaining scalable, high-performance applications.

*To be clear - this role is a leaning to back-end as 75% of your coding work will be back-end & 25% front-end *

You'll work closely with Product, Design and Engineering teams to deliver new features, improve platform performance and drive technical excellence across our applications. This is an ideal opportunity for a contractor who enjoys owning technical solutions, solving complex backend challenges and contributing to modern frontend experiences where required.

Key Responsibilities

• Backend Development (Primary Focus – 75%) with Ruby On Rails
• Design, develop and maintain scalable Ruby on Rails applications and services.
• Build robust, secure and well-documented RESTful APIs that power customer and installer platforms.
• Design efficient database schemas and optimise Postgres performance, including query optimisation, indexing, locking strategies and eliminating N+1 issues.
• Develop scalable backend architecture including background processing, caching, asynchronous jobs and third-party integrations.
• Write clean, maintainable, well-tested code following engineering best practices including Test-Driven Development (TDD), Continuous Integration and Continuous Delivery.
• Diagnose and resolve production issues, ensuring application performance, reliability and scalability.
• Continuously improve platform architecture, code quality and engineering processes.
• Frontend Development (Secondary Focus – 25%)
• Develop and enhance responsive user interfaces using React and Next.js.
• Integrate frontend applications with backend APIs with REST API.
• Build intuitive, cross-browser compatible user experiences across desktop and mobile devices.
• Contribute to frontend performance improvements and modern component architecture.
• Technical Leadership
• Own features from technical discovery through to production deployment.
• Collaborate with Product Managers to shape technical solutions, estimate work and identify delivery risks.
• Break complex business requirements into well-defined technical deliverables.
• Participate in architecture discussions and influence technical direction.
• Lead by example through high-quality engineering practices and constructive code reviews.
• Mentor other engineers and promote a culture of continuous learning and technical excellence.
• Identify opportunities to improve development tooling, CI/CD pipelines and engineering workflows.

Essential Skills & Experience

• 6+ years' minimum commercial software development experience.
• Expert-level Ruby on Rails development experience with a strong backend engineering background.
• Strong experience designing scalable APIs & REST API backend services and distributed systems.
• Solid understanding of Object-Oriented Analysis & Design (OOAD) and software engineering principles.
• Strong PostgreSQL experience, including schema design, SQL optimisation and database performance tuning.
• Experience implementing background workers, caching strategies and asynchronous processing.
• Experience writing automated tests using RSpec and maintaining high test coverage.
• Commercial experience with React and Next.js, including component-based development and API integration.
• Experience working within Agile software development teams.
• Strong Git workflow knowledge, including Pull Requests and Code Reviews.
• Excellent problem-solving skills with the ability to work independently as well as collaboratively.
• Passion for writing simple, clean, maintainable and efficient code.