We're currently looking for an experienced Senior Front-End Developer to come and join the Tribal team based in Paddington, London. 

Tribal (part of the Critical Mass agency) is a Total Experience agency. Thinking beyond the established customer experience, we work with brands to consider the total experience – online, offline and internal engagement and processes – and create products, services and comms that people love.

As a Senior Front-End Developer (SFED), you’ll play a pivotal role in shaping and crafting the user experience of our web applications. You’ll take ownership of the design and programming of both simple and complex websites, bringing your creative vision to life through innovative code. In this role, you’ll thrive working independently, while also collaborating closely with your Tech Lead to provide insightful solutions and accurate estimates for your tasks. You’ll immerse yourself in a diverse array of front-end technologies, including HTML5, CSS, and JavaScript, and you’ll be right at home with content management systems.

If you’re ready to make your mark and contribute to exciting projects in a vibrant team environment, we want to hear from you!

Our new hires & employees are the future of our organization, and we want to set you up for long-term success. In an effort to do so, we expect our team to work from the Tribal Worldwide London office a minimum of 3 days a week.

You will:

• Developing web applications that follow the latest web standards and conforms with leading-edge front-end technologies
• Works closely with Creative, Business, Technology and QA teams to ensure the solution will meet the requirements and performance targets (mobile, desktop).
• Owns the development of web applications and ensures they follow the overall technical architecture and design established by the technical lead
• Implements user and business requirements which are composed of multiple development activities
• Maintains up-to-date and complete documentation on projects as dictated by the capability’s guidelines and best practices
• Debugs or troubleshoots complex issues in existing web applications
• Proactively provide feedback on policies and procedures when an opportunity for improvement exists
• Proactively provide guidance and support to other members of the in fulfill their tasks and improvement their performance and overall technical skills.

You have: 

• At least 3 - 4 years of experience working with Front-End technologies (HTML/CSS/JavaScript)
• Excellent knowledge of recent development practices (Mobile First, MVC, Object Oriented development)
• Fluency in at least one major mainstream JavaScript library and/or framework ReactJS.
• Work experience with cross-browser and cross-device compatibility
• Work experience with automation and pre-processing tools (eg. Gulp, Grunt, SASS, LESS)
• Work experience integrating web solutions with external web services
• Knowledge of design patterns (e.g., model-view-controller, observer, object oriented, etc.)
• Experience pre-processing CSS styling (SASS, LESS).
• Fluency with data transfer formats and protocols popular in web applications (eg. JSON, XML, HTTP)
• Capable of writing code compliant with modern accessibility (eg. ARIA, WCAG, Microformats, ADA, RDF) and SEO guidelines and best practices
• Capable of working with version control systems (SVN, GIT, Mercurial)
• Capable of building proof of concept prototypes
• Capable of troubleshooting, debugging, and doing root cause analysis of web applications issues.
• Cloud knowledge: AWS, Azure, etc.
• Responsive design and development. 
• Desirable: BS in Computer Science or related technical discipline; or equivalent experience as Software Developer
• Desirable: Experience in Digital Agencies projects, Web development projects, SCRUM/Agile software projects. 

Critical Mass is an equal opportunity employer that is committed to diversity and inclusion in the workplace. We do not tolerate discrimination on the basis of race, national origin, gender, gender identity, sexual orientation, protected veteran status, disability, age, or other legally protected status. If you are an individual with disabilities who would like to request an accommodation, please reach out to accommodations@criticalmass.com.

We are committed to fostering diversity, equity, and inclusion within our pool of candidates, with a target of achieving at least 50% representation from underrepresented communities.

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#avoidIf Canada based: https://www.canada.ca/en/services/finance/consumer-affairs.htmlIf U.K. based: https://www.gov.uk/consumer-protection-rightsIf Costa Rica based: https://www.consumo.go.cr/educacion_consumidor/consejos_practicos.aspx