About the customer:Our customer is a key global player in patent data solutions, helping the world’s leading companies search, analyze, and leverage intellectual property. Their all-in-one SaaS platform streamlines every type of patent work: from drafting and prior art analysis to collaborative review and project management, all powered by advanced AI.About the project and the team:Underpinning the software is the treatment of the core patent data, what has been called the world’s greatest technical library, by deep cleaning and organising patent data from multiple sources, and allowing users to derive accurate patent status information, and drive visualisations of trends.The team comprises IP software specialists, patent search and data professionals, and patent attorneys, working within a hybrid working model that combines time spent in our offices in Chancery Lane, Central London, with remote working.About the role:Our Senior Full Stack Engineer will be responsible for developing, maintaining, and evolving key areas of the the website and related user-facing products. This role will work closely with the stakeholders and with external design and third-party development partners to ensure a high-quality, intuitive, and reliable user experience. Responsibilities:Design, build, and maintain the front-end interface for product delivery areas of the client application site, as agreed from time to time with product stakeholders, product designers, and the Technical Program Manager.Initially focusing on resolving known and documented bugs across existing products before contributing to ongoing enhancements and new feature development.Implement responsive layouts and ensure cross-browser/device compatibilityDeliver clean, intuitive UI/UX by working against a ticket-based backlog with direction, and, as projects evolve, collaborating more directly with product stakeholders. Collaborate with external developers and designers to ensure consistent branding, performance, and technical quality Ensure accessibility best practices (WCAG) across relevant areas of the site Optimise site performance through modern tooling, bundling, and code quality improvements Build and maintain additional sections of the client website as needed Develop and manage analytics and testing frameworks, including Google Analytics, event tracking, and A/B testing capability Provide basic database or API integration support, working alongside the back-end engineering team where appropriate Assist in documentation of front-end components, design patterns, and development processes Contribute to continuous improvement of development workflows, version control practices, and release processes Requirements:5+ years of experience working in standalone roles responsible for the development and maintenance of web interfacesStrong hands-on experience with PHP, JavaScript, React, Azure, D3, XML & JSONSolid experience with writing and maintaining automated tests including unit, integration, and end-to-end testsAbility to produce scalable, maintainable solutionsStrong time-management skills with the ability to handle multiple project-related tasks concurrentlyA proactive, positive approach to delivering high-quality workEnglish level - Upper-intermediate+ Nice to have:.NET Framework 4.6 MySQL or SQL Server experienceExperience setting up A/B testing or similar experimentation frameworksExposure to modern AI-powered development tools and workflows (e.g., code assistants, automated testing, or AI-driven UI optimisation)