SeniorDeveloper(FrontEnd)

The Critical Mass technology team is looking for an inspired, motivated, and experienced Senior Developer to join our Communications team for a contract engagement. We are an experience design agency with a focus on the customer, which means that collaboration and precision execution are at the heart of our process. You'll be working on high-visibility campaign and consumer-facing websites where pixel-perfect design execution and responsive optimization are critical to delivering a premium user experience. PLEASE NOTE – This is a contract position from July 1 – July 31, 2026 You Will: Deliver pixel-perfect front-end implementations that match design comps across all devices and viewport sizes Build responsive campaign layouts with modern animation-rich marketing pages using modern HTML, CSS, and JavaScript Work on individual components and page sections within robust, complex websites Collaborate with Design, UX, and the delivery team to ensure seamless implementation of designs Optimize page performance and ensure WCAG accessibility compliance Jump into high-velocity production work with minimal onboarding and deliver under tight timelines Take ownership of your work and drive solutions proactively with minimal supervision Support the team with clear code, documentation, and knowledge sharing You Have: 4+ years demonstrated experience using Vanilla JavaScript 5+ years’ experience using HTML5 semantic markup, CSS3, and CSS/SASS preprocessing 5+ years building SVG-based animations and responsive consumer-facing websites Strong expertise in pixel-perfect design implementation and responsive design across devices Full command of Git, the terminal, and modern development fundamentals Strong troubleshooting ability and technical analysis skills – including web performance optimization Proven ability to jump into projects quickly and deliver quality work under pressure Strong communication skills with a self-sufficient, collaborative approach to teamwork Fluency with impl