Senior Browser Extension Developer
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Senior Browser Extension Engineer
As a Senior Browser Extension Engineer, you'll play a key role in architecting and developing high-performance browser extensions that seamlessly integrate into our ecosystem. You'll tackle complex engineering challenges, influence key technical decisions, and contribute to both strategic architecture and hands-on implementation. Your work will help millions of users take control of their online privacy and security.
Responsibilities
Extension Development
• Architect and develop robust, high-performance browser extensions using TypeScript, React, and modern frontend tooling.
• Own the design and implementation of scalable, well-structured solutions to complex technical challenges.
• Clarify and solve ambiguous problems by identifying key requirements, breaking them down into manageable, testable components, and delivering well-engineered solutions.
• Assess and integrate third-party tools and libraries, making strategic decisions to balance trade-offs effectively.
• Drive performance optimisations by eliminating bottlenecks, enhancing UI responsiveness, reducing load times, and streamlining event handling.
• Quickly understand and debug unfamiliar code, using reverse engineering when required to analyse other extensions and diagnose issues effectively.
• Engineer fault-tolerant integrations that adapt to diverse website implementations, avoiding brittle solutions and ensuring graceful fallbacks.
• Stay ahead of the evolving web and browser extension ecosystem, spotting opportunities to drive impactful improvements in our products and
workflow.
• Uphold and improve engineering standards, ensuring best practices are maintained and continuously refined.
• Conduct thorough code reviews, enforcing high standards while mentoring junior engineers to level up their skills.
Collaboration & Integration
• Provide technical representation in cross-functional discussions, advising on feasibility, architectural considerations, and key trade-offs to guide
smart product decisions.
• Collaborate with the Browser Extension Team Lead to design elegant solutions that align with the long-term vision and integrate smoothly within
our ecosystem.
• Coordinate with engineers, designers, and product teams to align browser extension functionality with our app and web platforms, ensuring a
seamless user experience.
• Partner with support and QA teams to diagnose and resolve technical issues, ensuring critical fixes are quickly deployed to production.
• Review code for maintainability and best practices, mentoring engineers to improve code quality, system design, and problem-solving.
Security & Privacy
• Build privacy-first features, prioritising secure handling, storage, and transmission of sensitive data.
• Stay vigilant to security threats, applying fundamental browser security principles to proactively mitigate risks.
• Advocate for secure coding practices, implementing safeguards to protect user data while balancing privacy, security, and user experience.
Testing & Quality Assurance
• Improve test coverage for internal npm packages, writing unit and integration tests that validate public interfaces and remain resilient to
refactors.
• Drive modularity and maintainability by contributing well-documented, testable code across our libraries and browser extensions.
• Shape our automated testing strategy, exploring regression testing for browser extensions to streamline releases and catch issues early.
• Monitor extension performance, identifying regressions and ensuring a reliable user experience.
Experience & Qualifications
• 5+ years of commercial experience with TypeScript and React, including advanced TypeScript features and React performance optimisation.
• In-depth knowledge of front-end tooling (Redux, Webpack, Jest), leveraging these tools to maximise performance and scalability in large-scale, high-performance applications.
• Deep understanding of browser extension architecture and APIs, with hands-on experience implementing and maintaining complex features.
• Strong software engineering fundamentals, with proven expertise in event-driven and object-oriented programming and their associated design patterns to build scalable, performant, and maintainable systems.
• Ability to make well-reasoned technical decisions, considering all factors, including complexity, long-term maintainability, and how quickly the team
can get up to speed.
• Strong JavaScript expertise, including asynchronous programming, event loop mechanics, closures, and functional patterns.
• Strong debugging skills, able to analyse unfamiliar code, resolve complex bugs, and optimise event-driven systems.
• Experience mentoring and guiding junior engineers through thoughtful code reviews and promoting high technical standards.
• Passionate about software craftsmanship, owning solutions, improving code quality, and driving best practices.
• Effective communicator, bridging technical and non-technical teams to advocate for balanced solutions and explain complex concepts clearly.
What we offer in return:
Our staff work hard for us, so in return for this, alongside various company events, a fantastic office space and a great team culture, we offer -
• Salary: £50,000 - £60,000
• Up to 10% annual personal performance based bonus
• 28 days annual leave, plus length of service accrual
• Breakfast, lunch, drinks & snacks provided
• Company pension
• BUPA Health & Dental care
• Death in Service benefit
• BUPA Peak Assessments
• Netflix & Spotify subscriptions
• Gym & Golf Membership
• Beer fridges & onsite cocktail bar
• Onsite hairdressers
• + Many more!