Senior Developer, Front End

6 Hours ago • 5 Years +

Job Summary

Job Description

Critical Mass is looking for a Senior Front-End Developer to join their team. This role involves collaborating with designers and UX specialists, leading development using Vanilla JavaScript, and building and maintaining components using React, Vue, and jQuery with native JavaScript for optimal performance. The developer will also create web animations using GSAP/GreenSock, integrate dynamic content from JSON or markdown sources, write modular styles with SASS, ensure cross-device compatibility and performance, and mentor junior developers. This is a contract position.
Must have:
  • 5+ years of experience building consumer-facing websites with 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 for seamless experiences
  • Proven expertise with GSAP/GreenSock for 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
  • 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
Good to 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

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 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

 

Please note the salary range below is hourly. 

 

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.

Salary Range

$90 - $90 USD

Critical Mass is an equal opportunity employer. 

The Critical Mass Talent Acquisition team will only communicate from email addresses that use the URLs criticalmass.com and us.greenhouse-mail.io. We will not use apps such as Facebook Messenger, WhatsApp, or Google Hangouts for communicating with you. We will never ask you to send us money, technology, or anything else to work for our company. If you believe you are the victim of a scam, please review your local government consumer protections guidance and reach out to them directly.

If U.S. based: https://www.consumer.ftc.gov/articles/job-scams#avoid
If Canada based: https://www.canada.ca/en/services/finance/consumer-affairs.html
If U.K. based: https://www.gov.uk/consumer-protection-rights
If Costa Rica based: https://www.consumo.go.cr/educacion_consumidor/consejos_practicos.aspx 

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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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