Developer jobs in United Kingdom

We believe in rewarding expertise and accountability, which is why we offer an excellent salary. This includes 25 days holiday plus bank holidays, an additional day off for your birthday, a collaborative and supportive working environment, and the opportunity to work closely with senior leaders who value clarity, technical judgement, and delivery.

• Supporting and contributing to the Ruby on Rails orchestration layer, helping to reduce technical risk and ensure the platform is robust, scalable, and well understood
• Supporting the team through a period of significant scale, providing hands‑on technical expertise to stabilise, improve, and evolve the existing codebase
• Working closely with stakeholders to help secure the technical foundations needed for Complii s future vision of connected customer technology
• Contributing to architectural decisions, code quality, and best practices, while accelerating delivery and confidence across the engineering function

• Strong experience using the Ruby on Rails framework, with supporting knowledge of technologies such as Postgres, Redis, Sidekiq/ActiveJob, and HTML/jQuery
• Experience designing and working with APIs, including third‑party integrations, and deploying applications using Heroku or similar PaaS providers
• A pragmatic approach to problem‑solving, with a focus on simplicity, risk reduction, and building solid technical foundations
• A collaborative mindset, strong communication skills, and the ability to make a tangible impact within the first 90 days

At Complii, we are on the lookout for a Senior Developer to play a key role in strengthening and scaling a business‑critical technology platform. This role is focused on reducing risk, supporting significant scale, and helping secure the technical foundations needed to deliver our long‑term vision of connected customer technology. If you enjoy working on complex systems, bringing clarity to areas of technical uncertainty, and having real influence over architectural decisions early on, this is a role where your impact will be felt quickly and meaningfully.

If you feel you have the skills and drive to make an impact, even if you don t meet every requirement above, we d still love to hear from you. Complii is a leading integrated provider of safety and regulatory compliance services across our water, air, fire, and electrical divisions, supporting organisations nationwide to operate safely, compliantly, and responsibly. This is a fully remote role and can be based anywhere in the UK, offering the opportunity to shape a critical platform and make a lasting difference.