Senior Developer, Front End

5 Hours ago • 5 Years +

Job Summary

Job Description

The Senior Front-End Developer will be responsible for developing innovative, visually compelling, and high-performance web experiences using modern JavaScript technologies. This role involves collaborating with designers and UX specialists to create interactive experiences, using technologies like React, Vue, jQuery, and Three.js. The developer will also be responsible for ensuring cross-device compatibility, accessibility, and optimal page performance. Mentoring junior developers and contributing to code reviews are also essential parts of the role.
Must have:
  • 5+ years of experience in building consumer-facing websites with Vanilla JavaScript
  • Deep understanding of HTML5 with at least 5 years of experience
  • Advanced expertise in CSS3
  • Proficient in SASS
  • Strong command of responsive design principles
  • Proven expertise with GSAP/GreenSock
  • Experience building interactive graphics with WebGL and Three.js
  • Hands on experience with Handlebars (HBS) for dynamic templating
  • Familiarity with React, Vue, and jQuery
  • Strong Git proficiency and experience with modern development workflows
  • Solid troubleshooting and performance optimization skills
  • Strong communication skills and ability to work collaboratively
Good to have:
  • Experience with advanced CSS methodologies or custom style languages
  • Demonstrated ability to push the boundaries of web technology
  • Familiarity with content management systems (CMS), such as Adobe Experience Manager (AEM)
  • Agency experience
Perks:
  • 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
  • Diversity and Inclusion Board with 12 affinity groups
  • Internal learning and development programs
  • Enterprise-wide employee discounts

Job Details

Critical Mass is looking for a talented and motivated Senior Front-End Developer to join our technology team, responsible for delivering innovative, visually compelling, and high-performance web experiences using modern JavaScript technologies. This is a unique opportunity to work with a high-profile client, collaborating closely with design, UX, and engineering teams to create best in class digital communications and interactive experiences.

Please note this is a hybrid, contract position.


You will:

  • Collaborate with designers and UX specialists to rapidly prototype and implement engaging user interactions
  • Lead development using Vanilla JavaScript (no frameworks) and modern frontend standards
  • Build and maintain components using technologies like React, Vue, and jQuery—all implemented in native JavaScript for optimal performance and extensibility
  • Develop visually rich, interactive 3D animations utilizing WebGL and Three.js
  • Create high impact web animations and transitions using GSAP/GreenSock
  • Integrate dynamic content from JSON or markdown sources using Handlebars (HBS) templating
  • Write modular, maintainable styles with SASS, leveraging its advanced capabilities for scalable CSS architecture
  • Ensure cross device and cross browser compatibility, accessibility (WCAG), and optimal page performance.
  • Mentor junior frontend developers and contribute to code reviews, documentation, and testing best practices.

 

You have:

  • 5+ years of professional experience building consumer facing websites with advanced skills in Vanilla JavaScript
  • Deep understanding of HTML5 with at least 5 years of experience
  • Advanced expertise in CSS3, with a strong focus on styling, layout, and design
  • Proficient in SASS for writing modular, maintainable, and scalable stylesheets
  • Strong command of responsive design principles to ensure seamless experiences across all devices
  • Proven expertise with GSAP/GreenSock or similar animation libraries to deliver smooth, high quality web animations
  • Experience building interactive graphics or 3D web experiences using WebGL and Three.js
  • Hands on experience with Handlebars (HBS) for dynamic templating, including ingestion of JSON and markdown sources
  • Familiarity with React, Vue, and jQuery, including implementing these patterns with Vanilla JS
  • Strong Git proficiency and experience with modern development workflows (CI/CD, terminal, etc.)
  • Solid troubleshooting and performance optimization skills
  • Strong communication skills and ability to work collaboratively in a distributed team environment
  • Experience working with enterprise level CSS systems or custom extensible design languages
  • Knowledge of web accessibility standards (WCAG) and best practices
  • Familiarity with content management systems (CMS), such as Adobe Experience Manager (AEM), or API driven architectures
  • Experience with build tools like Webpack and task runners

 

Bonus if you have:

  • Experience with advanced CSS methodologies or custom extensible style languages
  • Demonstrated ability to push the boundaries of web technology with innovative UI/UX
  • Familiarity with content management systems (CMS), such as Adobe Experience Manager (AEM), or API driven architectures
  • Agency experience

 

 

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
  • Diversity and Inclusion Board with 12 affinity groups
  • Internal learning and development programs
  • Enterprise-wide employee discounts

 

 

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About The Company

Critical Mass is a team of 1,800 inspired folks based in 12 offices around the world, providing full-service digital capabilities for the greatest brands on Earth. Our secret sauce is our uncompromising design standards, our relentless focus on customers, and an ability to put powerful new technologies to work for our clients.


We work with the best—Apple, Nike, Mars Wrigley, Nissan, Diageo, Airbnb, BMW, BNY Mellon, Johnson & Johnson, and many more—brands who strive for connected digital ecosystems and unparalleled experiences. We help them get there by gaining deep insight into their consumers and orchestrating data, AI, design, media, and tech stacks around human stories.


We’re a global agency founded in Canada, but digital is our home. If you know us, then you know we’re a special, quirky place that attracts big talent and tiny egos. (We actually give out a “so f-n nice” award—lots of them). But just because we’re friendly doesn’t mean we’re not a force to be reckoned with. We’re driven. Relentless. And we live our values. We’re Critical Mass, but our friends call us CM. Please call us CM!

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