Senior Full Stack Developer (Contractor)

This position is listed on behalf of a partner company, who manages all applications and next steps. Our partner is looking for a Senior Full Stack Developer (Contractor) based in Canada. This is a hands-on engineering role focused primarily on building intuitive, performant, and accessible digital experiences. You will take ownership of user-facing features from design handoff through deployment while contributing to backend development when needed. The role combines strong front-end expertise with practical experience across APIs and Ruby on Rails-based services. You will work closely with product managers, designers, and engineers to turn ideas into polished, scalable product experiences. Performance, accessibility, maintainability, and usability will be central to the work you deliver. As a senior contributor, you will also help establish engineering standards, review code, mentor teammates, and improve technical practices. The environment values ownership, thoughtful collaboration, continuous learning, and a strong user-first mindset. Build, maintain, and improve user-facing features within a modern single-page application, taking ownership from design handoff through production deployment. Translate product requirements, user needs, and design mockups into clean, scalable, reusable, and maintainable front-end code. Develop primarily with JavaScript, HTML, CSS, and modern front-end frameworks, with the ability to work effectively across the stack when required. Collaborate closely with product managers, designers, and backend engineers to deliver high-quality features from concept through implementation. Contribute to backend logic and REST APIs within a Ruby on Rails environment when necessary. Maintain consistent implementation of design systems, UI patterns, and product standards across the application. Optimize applications for performance, responsiveness, reliability, and cross-browser compatibility. Write well-tested, maintainable code and participate actively in technical discussions and code reviews. Incorporate accessibility best practices and WCAG principles into front-end development to create inclusive user experiences. Identify and address technical debt, architectural limitations, and opportunities to improve front-end systems. Help establish front-end development standards, tooling practices, and technical guidelines. Mentor junior and mid-level engineers through constructive feedback, technical guidance, and code reviews. Investigate and resolve technical issues across the front end and, when appropriate, the backend. Stay current with emerging front-end technologies and apply relevant improvements to development practices and product capabilities. Requirements 5+ years of professional experience in front-end or full stack software development. Strong proficiency in JavaScript, HTML, and CSS, with hands-on experience building single-page applications using a modern front-end framework. Experience with Svelte is advantageous, while strong experience with React, Vue, or a comparable framework is also relevant. Comfortable working with REST APIs and contributing to backend development when required. Experience with Ruby on Rails or another backend framework is a strong advantage. Strong understanding of front-end architecture, reusable components, responsive design, and application performance. Demonstrated ability to write clean, maintainable, and well-tested production code. Strong understanding of accessibility principles and experience incorporating WCAG or inclusive design practices into web applications. Strong attention to detail and a user-first approach to product development. Excellent communication skills and the ability to collaborate effectively with product, design, and engineering teams. Comfortable providing mentorship and constructive technical feedback to less experienced engineers. Ability to work independently, take ownership of deliverables, and make sound technical decisions. Experience