Senior Backend Engineer (Ruby)

Senior Backend Engineer (Ruby) Role type - Permanent Location - London (Hybrid) About Zuno Zuno is the UK’s biggest home energy installer, helping thousands of customers make their homes warmer, smarter and more energy efficient We’re a fast-growing team backed by Brookfield and part of the HomeServe Group, working with major household names including E.ON, EDF Energy, Worcester Bosch, B&Q and Tesla. Join Zuno and be part of the team shaping the future of home energy in the UK. The role We’re looking for someone to be part of a fast paced product team, building the robust core services that drive experiences for our customers, installers and operations team. As a Senior Backend Engineer, you will be acting as a technical anchor within the team, defining the architectural direction of our server-side logic and ensuring the scalability of our data models. You will partner with Product Managers to shape the roadmap and ensure technical feasibility from the outset. In this role, you will be responsible for designing and optimising high-performance APIs and complex business logic using Ruby on Rails. While your focus is backend, you will work closely with frontend engineers to define API contracts and ensure seamless integration with our Next.js frontend. You'll also contribute to keeping the quality of the code top-notch by reviewing your teammates' code and mentoring junior engineers. Key responsibilities Core Backend Architecture: Design, build, and maintain robust, scalable, and secure backend features using Ruby on Rails, ensuring business logic is encapsulated and efficient API Strategy: Architect and document performant RESTful APIs, acting as the bridge between server-side logic and the React/Next.js frontend teams Technical Leadership: Lead technical discussions on system design, database schema planning, and the decoupling of monolithic services where necessary Performance & Scalability: Proactively identify and resolve performance bottlenecks, focusing on SQL query optimisation, caching strategies (Redis), and background job management (Sidekiq/Solid Queue) High-Quality Engineering: Write clean, maintainable, and efficient code that adheres to best practices (including Test-Driven Development and Continuous Delivery) Feature Ownership: Take ownership of complex backend features from concept to deployment; assisting the Product Team in scoping requirements and managing technical debt Driving Engineering Culture: Act as a catalyst for technical excellence by evolving our backend engineering standards (OOAD, SOLID principles) and internal processes. You will proactively identify and resolve bottlenecks, whether in code, deployment, or communication, advocating for the changes needed to make the backend team faster, safer, and more efficient. Mentorship: Actively mentor junior and mid-level engineers, fostering a culture of continuous learning and technical excellence System Reliability: Debug and resolve…