The Critical Mass technology team is looking for an inspired, motivated, and experienced Senior Front End Developer to join our team. We are an experience design agency with a focus on the customer, which means that multi-discipline collaboration and prototyping are at the heart of our process. We're using the latest technologies including React, ES6 JavaScript, pub/sub architecture, and a clean component-based approach to deliver reusable, innovative, and responsive experiences. Web performance & accessibility are also key concerns because of their respective importance to user experience and perception of a premium experience. * Please note- you must be located in The Bay Area and be available to work on site in our Cupertino office You Will: * Collaborate with Design and UX to prototype user interactions * Mentor junior front-end developers * Ensure compatibility of code across devices and viewport sizes * Assess and optimize page performance and WCAG compliance * Develop and implement high-performance, visually engaging web animations using GSAP, GreenSock, or similar animation libraries to enhance user experience and interactivity * Work with delivery team to ensure overall quality of the experience and support this with tests and documentation You Have: * Strong communication skills with a team-centric approach to discussion and decision making within a distributed team * 4+ years demonstrated experience using Vanilla Javascript * 5 + years experience using HTML5 semantic markup, CSS3, and CSS & SVG-based animation on responsive consumer-facing websites * Proficiency in GSAP, GreenSock, or similar web animation libraries for creating high-quality, interactive animations * Full command of Git, the terminal, continuous deployment and integration, and other modern fundamentals * Strong troubleshooting ability and technical analysis skills - web performance optimization included * Familiarity with website operations and fluency in the typical tiers on a high traffic website * Experience with the Atlassian suite of tools - JIRA, Bitbucket, Confluence, etc. * WCAG accessibility experience is preferred You May Have: * Adobe Experience Manager (AEM) on version 6.3 or later, or enterprise CMS * Experience with graphQL or APIs with complex data structures * Experience with Webpack, or other tools used to optimize and maintain front-end build systems * Experience working in an agency environment * A -very strong- meme game What We Offer: * Global maternity and parental leave * Competitive benefits packages * Vacation, compassionate leave, sick days, and flex days * Access to online services for families and new parents * 13 affinity groups * Internal learning and development programs * Enterprise-wide employee discounts We continually review ranges to address skills, experience and markets. Base salaries are determined during our interview process, by assessing a number of factors that include, but aren't limited to, a candidate's experience and skills relative to the scope and responsibilities of the position. For current CM employees, tenure will also be a consideration.