Senior Software Engineer in London

We’re looking for a Senior Software Engineer for one of our CMS product teams, working from the UK, to help us shape the future of Optimizely’s products and offerings. We’re at the top of industry analyst ratings and pushing to take both the PaaS and SaaS versions of our CMS further. A big part of that push is Opal, our always-on AI workforce that improves productivity for content teams. Building on that capability is one of the things that makes this moment particularly interesting.

You’d join a group of teams with many senior engineers who have deep product knowledge and diverse technical backgrounds. Personal and cultural fit matters as much as skills and experience here. The team collaborates closely, both remotely and in person, with a culture built around trust and open communication. We have an office in London, and if you’re based there, we’d expect you to work from the office a few days per week. If you’re elsewhere in the UK, we fully support remote work. We care about work-life balance in practice, not just on paper. We work across time zones but respect local working hours, family commitments, and your physical and mental health. There are occasions where a critical production issue or urgent release requires work outside normal hours, but that is the exception, not the norm. Many of us have been here a long time. That’s not inertia, it’s because the work stays interesting and the environment is healthy.

What You'd Do

• Design, implement, and document software solutions that are simple, secure, scalable, and maintainable.
• Own the operational excellence of your domain, including instrumentation, monitoring and alerting.
• Ensure product quality through thorough automated testing.
• Drive delivery of complex features end-to-end, working across team boundaries when needed.
• Contribute to architecture and design discussions within your team and across teams, communicating decisions through design docs and knowledge-sharing forums.
• Participate in project planning, requirements gathering, design, and task refinement.
• Handle incidents and assist our support organisation when they need engineering expertise on customer cases.
• Bring customer perspective into technical decisions, understanding how the product is used in practice.
• Mentor other engineers and share knowledge across the team.
• Participate in hiring and help grow a diverse engineering organisation.

What We're Looking For

We value personal and cultural fit as much as technical skill. You are self-motivated, enjoy collaborating to find the right solution, and you think about architecture, development cost, and long-term ownership when making decisions. You’re comfortable working through ambiguity, can articulate trade-offs clearly, and leave projects in a state where someone else can pick them up.

Must have:

• Typically 8+ years of professional experience with modern software development practices, though we recognise some people get there faster.
• Strong software design and engineering fundamentals, including object-oriented analysis and design.
• Solid experience with C# and .NET, and with React on the frontend.
• Hands-on experience with CMS platforms, content modelling, or digital experience tooling.
• You understand the domain and the problems content teams face.
• Experience building and operating cloud-based software.
• Already using AI tools, coding assistants, and potentially agents as part of your daily workflow to improve both quality and speed.
• Comfortable working in an agile environment alongside designers, product managers, and other stakeholders.
• Good communicator who enjoys solving problems together with others.

Good to have:

• Experience with Optimizely CMS or other CMS/DXP platforms.
• .NET Core MVC.
• SQL (particularly MS SQL).
• Containers and container orchestration.
• HTTP APIs, REST services, or GraphQL.
• Experience building large, modular applications with continuous delivery.
• A degree in Computer Science or equivalent. We care more about what you can do than what’s on your diploma.

Optimizely is committed to a diverse and inclusive workplace. Optimizely is an equal opportunity employer and does not discriminate on the basis of race, national origin, gender, gender identity, sexual orientation, protected veteran status, disability, age, or other legally protected status.