CRO Optimisation Engineer

The CRO Optimisation Engineer is a highly specialised front-end developer and platform expert responsible for the technical build, deployment, and performance validation of digital experiments and personalization campaigns across Sonova’s global web estate. Operating as the technical engine of the CRO sub-pod, this role bridges the gap between optimisation design and live execution. Writing clean, high-performance client-side and server-side code directly within our experimentation platforms (e.g., Optimizely) to bypass standard release bottlenecks while protecting core platform speed, code cleanliness, and user experience. In this role, you will be in charge of: Technical experiment development: build, code, and configure robust A/B, multivariate, and personalisation tests within Optimizely using custom JavaScript, HTML, and CSS, eliminating reliance on restrictive WYSIWYG visual editors.Code Performance & mitigation: ensure all optimisation scripts are exceptionally lightweight and performant. Actively engineer technical solutions to prevent asynchronous layout "flickering" or performance degradation to safeguard core platform speed and Core Web Vitals.Responsive mobile engineering: ensure all experimental variants are completely optimised, responsive, and cross-browser compliant across desktop, tablet, and mobile breakpoints.Advanced analytics data tagging: Partner with the analytics specialists to deploy custom event tracking, data layer pushes, and analytics configurations to guarantee pristine data capture for all live experiments.Pre-Launch quality assurance: Lead exhaustive technical QA and browser testing on all variant builds prior to launch, verifying that user journeys, forms, and lead capture mechanisms function flawlessly.Behavioural tool integration: Manage the technical integration and custom tagging setup for qualitative behavioural tools like FullStory and Qualtrics to capture deep visitor interaction data. Your background: 3+ years of dedicated front-end development experience with a heavy focus on digital optimisation, user experience engineering, or conversion-focused growth marketing.Proven track record writing sophisticated, custom JavaScript and CSS modifications within enterprise-level experimentation engines (specifically Optimizely or closely related architectures).Extensive experience debugging complex front-end code layout issues, DOM manipulation scripts, and cross-browser styling anomalies.Hands-on experience configuring analytical event-tracking structures, data layers, and custom tag variables.Expert-level mastery of native JavaScript, semantic HTML, CSS pre-processors, and asynchronous coding methodologies.Deep technical understanding of web performance optimization concepts (e.g., DOM manipulation speeds, critical rendering path, minimizing blocking time).Strong familiarity with modern behavioral analytics platforms (FullStory, Hotjar) and enterprise quantitative packages (GA4). How we work: At Sonova, we prioritize the well-being of our employees and foster an inclusive environment that promotes engagement and collaboration. Our team-customized hybrid work model empowers teams to balance individual needs with business goals, offering flexibility and individualized time management. We recognize the importance of life outside of work and strive to create a supportive and motivating workplace where innovation thrives. Sonova is an equal opportunity employer. We team up. We grow talent. We collaborate with people of diverse backgrounds to win with the best team in the market place. We guarantee every person equal treatment in regard to employment and opportunity for employment, regardless of a candidate’s ethnic or national origin, religion, sexual orientation or marital status, gender, genetic identity, age, disability or any other legally protected status.