Senior Backend Engineer

London | Hybrid (2 days per week onsite) Who are Zuno?Zuno is a global digital platform transforming how installations happen in our homes. With over 15,000 engineers on our platform, we connect leading brands, technology and skilled people to make home installations simpler and more efficient.We partner with some of the biggest names in the industry, including E.ON, EDF Energy, Worcester Bosch and Tesla, helping bring products ranging from boilers and solar panels to battery storage and EV chargers to life.What makes us different? Our digital first approach. Think about what Uber did for taxis and Amazon did for retail. Zuno is bringing that same digital-first thinking to home energy. We're growing fast, creating opportunities to make an impact, take ownership and help shape what comes next.The roleAs 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 ResponsibilitiesDesign, build and maintain scalable, secure backend features using Ruby on Rails.Design and maintain RESTful APIs to support our React/Next.js frontend teams.Lead technical discussions around system architecture, database design and improving our modular monolith.Optimise application performance, including SQL queries, caching and background jobs.Write clean, maintainable, well-tested code, following engineering best practices and CI/CD processes.Own complex backend features from planning through to deployment, working closely with Product to scope requirements and manage technical debt.Identify and implement improvements to code quality, deployment processes and engineering workflows.Mentor junior and mid-level engineers and help raise technical standards across the team.Troubleshoot production issues and maintain system reliability, availability and data integrity.Skills & Experience5+ years' professional backend development experience.Strong expertise in Ruby and Ruby on Rails, including framework architecture and metaprogramming.Excellent knowledge of PostgreSQL, database design and SQL optimisation, including N+1 queries and database locking.Strong understanding of object-oriented design, design patterns and software engineering principles.Experience designing and maintaining versioned, documented RESTful APIs.Experience writing automated tests using RSpec, including integration and request specs.Familiarity with Agile methodologies, Git, pull requests and code reviews.Strong problem-solving skills, with a proactive approach to identifying and implementing technical improvements.Excellent communication skills, with the ability to collaborate across engineering, product and non-technical teams.Beneficial Skills (Not Essential)Experience with AWS, Docker, Kubernetes or Infrastructure as Code.Familiarity with React, Next.js or TypeScript.Experience with background processing tools such as Sidekiq.Knowledge of Site Reliability Engineering (SRE), monitoring and observability tools such as New Relic.Benefits30 days annual leave + bank holidays!Private medical cover with Aviva*4 x salary Death in Service cover with Zurich*Paid 6 months maternity pay after a year of servicePaid paternity pay after a year of service£1000 annual training budget*Salary sacrifice pension matched up to 6%Flexible working times and locationCompany MacBook Pro & accessoriesTeam lunches, team eventsAfter probationary period*Please note: We’re unable to offer visa sponsorship for this role, so candidates must already have the right to work in the UK.