Senior Software Engineer

We're not here to add to the noise. We're here to cut through it- with AI that actually works for marketers. From AI-powered content creation to world-class CMS and the industry's most trusted experimentation platform, Optimizely is the tool modern marketers actually want to use. AI-Ready. Set. Go. 10,000+ brands including H&M, PayPal, and Zoom already get it. So do Gartner, Forrester, and IDC, who consistently recognize us as leaders in MarTech. But here's the thing about building great products: it takes great people. Our 1,600+ Optimizers across 12 global offices are curious, collaborative, and refreshingly human. We don't do corporate speak. We do real conversations, big ideas, and genuinely care for the work we make together. If you want to be part of a team that's shaping the future of marketing technology — and actually enjoys doing it — you're in the right place. Find us on Instagram: @optimizely Long Description We're looking for a Senior Software Engineer to join one of our Content Management System (CMS) product teams in the UK, working on a key part of the Optimizely platform. Our CMS is one of the core products in the Optimizely ecosystem. It enables businesses to create, manage, and publish digital content—such as websites, landing pages, and product experiences—across multiple channels. It works alongside other parts of the platform, including experimentation, campaign management, and data services, to support end-to-end digital experience creation and optimization. We offer both PaaS and SaaS versions of our CMS and are continuously evolving it to be more scalable, composable, and developer-friendly. As part of this team, you'll help build and evolve core CMS capabilities while contributing to the long-term direction of the platform. Introduction About The Team Our team focuses on building extensible CMS capabilities and integrations that make the platform more flexible and useful for customers. This includes developing add-ons such as: Forms – a flexible form-building capability that allows users to create and manage dynamic forms based on predefined UX layouts, without requiring developer involvement. Forms can be structured using rows, columns, and reusable elements, enabling editors and marketers to quickly build and update forms while still supporting advanced customization when needed. Language Manager – enabling editors to work efficiently with multilingual content AI tools & agents – we are building AI-powered capabilities to streamline how forms and content experiences are created and managed. This includes generating forms dynamically from design inputs (e.g., Figma) or user intent, reducing manual composition while applying best practices by default. We also explore using agents to connect our add-ons with other parts of the ecosystem (e.g., Campaign, Optimizely Data Platform), helping automate workflows, reduce friction, and enable more seamless data flow across systems. These capabilities are supported by the Opal Orchestrator platform, which underpins how AI-driven workflows are designed and executed across the product. In addition, we integrate the CMS with external systems and services, helping it fit into a wide range of customer architectures. This includes ingesting data from other Optimizely products and enabling seamless data flow into marketing automation systems to support high-impact campaigns. A significant part of our work involves designing and maintaining REST APIs that expose CMS functionality and enable flexible, composable use of the platform. Our CMS is not just a product—it's also a platform used and extended by a global developer community. Customers and partners build custom solutions, integrations, and extensions on top of it. Because of that, we place strong emphasis on clean, well-structured code, clear abstractions, and solid separation of concerns. We aim to provide stable APIs and extension points that make the platform easy to customize and build upon. You'll be joining a group of experienced engineers with deep product knowledge and diverse technical backgrounds. While engineers on this team are based in Hanoi, Vietnam, the wider CMS organization spans the US, UK, Stockholm, Vietnam, and Bangladesh. We value collaboration, open communication, and shared ownership across these global locations. We have an office in London and support a hybrid setup. If you're based elsewhere in the UK, we also support fully remote work. How We Work We're a global company, and our teams collaborate across time zones while respecting local working hours and personal commitments. We care about work-life balance in practice. Occasionally, there may be urgent production issues or releases that require extra effort, but this is the exception rather than the norm. Many engineers stay with us long-term because the work remains interesting and the environment is supportive. Job Responsibilities Design, build, and maintain scalable, maintainable software systems Develop CMS features, add-ons, APIs, and integrations with external systems Contribute to system design and architectural decisions Ensure product quality through automated testing and operational best practices Own services in production, including monitoring and incident handling Collaborate with product managers, designers, and engineers to deliver features end-to-end Consider real-world usage and customer needs in technical decisions Mentor other engineers and contribute to knowledge sharing Participate in hiring and help grow the engineering team Knowledge And Experience Must have ~8+ years of experience in software engineering (flexible depending on experience)Strong fundamentals in software design and engineeringExperience with C# and .NET, and React on the frontendExperience with CMS platforms, content modelling, or similar domainsExperience building and operating cloud-based systemsComfortable using AI tools (e.g., Claude or similar) in your daily workflow for problem solving, learning, and improving code quality and delivery speed; able to guide AI-assisted development using structured instructions (e.g., well-defined prompts or Markdown-based instruction files) to generate code in a controlled and maintainable way, with interest or experience in leveraging AI agents to further enhance productivityStrong testing mindset, with a focus on building reliable, well-tested systems and maintaining high code qualityComfortable working in cross-functional, agile teamsStrong communication and collaboration skills Nice to have Experience with Optimizely CMS or similar CMS/DXP platforms.NET Core / MVCSQL (especially MS SQL)REST APIs or GraphQLContainers and cloud platforms (e.g., Azure)Experience building modular systems with continuous deliveryExperience building AI-powered features (e.g., RAG systems, LLM integrations)Degree in Computer Science or equivalent experience Education Bachelor’s Degree (Computer Science or engineering preferred) or equivalent work experience 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.