Job Description

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 – September 25, 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 implementing pre-made components from a component library such as Material UI or similar
Proven knowledge using utility classes, grid classes, and utilizing CSS frameworks such as Bootstrap, Foundation, Materialize, or similar
Experience with navigating Sketch design files to find font and color styles and dimensions
Proven track record of delivering production-quality code on high-visibility projects
Practice or exposure to developing software with Large Language Models (LLMs), including writing and integrating AI-assisted code
Experience with web animations (CSS and JS) and web animation libraries (GSAP)

Bonus if you Have:

Capability with Handlebars or other templating engines
Skill with Webpack or other front-end build system optimization tools
Experience working in an agency or fast-paced production environment
Familiarity with design-to-development handoff processes and design systems
Awareness with the Atlassian suite of tools (JIRA, Bitbucket, Confluence)
WCAG accessibility expertise

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

$13,000—$142,000 USD

Critical Mass is an equal opportunity employer.

Critical Mass uses artificial intelligence in our recruitment process to enhance job postings, filter keywords during the review of prospective candidates, and, in some cases, transcribe interviews with our recruiters. Human review remains central to the process, and all hiring decisions are ultimately made by our team.

The Critical Mass Talent Acquisition team will only communicate from email addresses that use the URLs criticalmass.com, omc.comand 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

About Critical Mass

Critical Mass is a team of 1,900 inspired folks based in 13 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!

Industry

Marketing & Advertising

Company Size

1,001-5,000 employees

Headquarters

Calgary, CA

Year Founded

Unknown

Website

criticalmass.com

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