Senior Front-end Developer (Performance & Optimisation)

2025 is all about GROWTH for us here at Squiz 🚀, and we are looking for a Senior Front-end Developer (Performance & Optimisation) to join our dynamic Professional Services team.

This is a unique opportunity to participate in the development and optimisation of high-performance user interfaces and complex components for digital solutions. You'll play a pivotal role in ensuring our projects deliver exceptional speed, efficiency, and user experience, while mentoring others and driving technical excellence in front-end performance and optimisation.

In this role, you'll work alongside a talented team of professionals, contributing to projects that set new benchmarks for performance, usability, and innovation. We're seeking someone who is passionate about frontend performance, thrives on solving complex challenges, and is eager to make a significant impact on client success and our technical direction.

Why Squiz?

You'll work with some of the most intelligent and down-to-earth people you'll ever meet. We are a diverse team of passionate professionals who love challenging the status quo. Every day is different, but one thing that's constant is that we all love what we do.

We are deeply committed to flexibility because we understand that our people's success depends on maintaining a balanced life. With our flexible working policy will have the flexibility to choose where and how you work each day. Our goal is for you to work in a way that fosters productivity, efficiency, and positive outcomes, while also encouraging connection and collaboration.

At Squiz, we celebrate diversity and unite on the elements of our company DNA, starting every customer conversation with "why?" to really understand their needs, working hard to find a way to overcome every challenge, and fighting for better outcomes with the work we do. We also check our egos at the door, we don't take ourselves too seriously, and we have fun along the way.

We invest in your growth: from access to the latest tools and technologies, to regular knowledge-sharing sessions and opportunities to lead innovation initiatives. You'll have the chance to shape the future of digital experiences for leading organisations, while developing your own expertise in a supportive, forward-thinking environment.

Salary & Benefits:

- Contract of Employment - full time, permanent after a 3-month probationary period. Unfortunately, we do not offer B2B contracts.

- Base salary: 15 000 - 22 000 PLN/month gross

- Hybrid (Szczecin office day once a week)

- Flexible working time (core business hours between 9:00 - 15:00)

- 30 days of paid leave per annum, regardless of the length of service

- 1000 PLN annual wellbeing bonus

- Free online English classes

- Private health package and group insurance

- Subsidised lunch when working from the office

- Free parking spaces

Who you are:

- Demonstrated experience in leading complex front-end projects, including project planning, writing specifications, resource allocation, risk management, and delivery of high-quality solutions

- Expert-level proficiency in front-end performance and optimisation: advanced HTML, CSS, JavaScript, bundlers and modern frameworks (React-focused would nice)

- Mastery of performance tools: Lighthouse, WebPageTest, Chrome DevTools, and profiling techniques

- Deep expertise in optimisation techniques: code splitting, tree shaking, lazy loading, image optimisation, progressive loading and others

- Experience making architectural decisions that prioritise speed, efficiency, and user experience

- Advanced understanding of browser rendering, critical rendering path, and performance bottlenecks

- Excellent client-facing skills for running technical projects, reviews, and workshops

- Proven experience mentoring and guiding technical growth in client-side engineering

- Proficiency with modern front-end tooling: webpack, Vite, build optimisation, and agile workflows

- Fluent English and Polish language skills (is a must)

What you'll do:

- Deliver high-quality technical solutions on day-to-day projects that meet and exceed client expectations

- Lead the development and optimisation of high-performance DXP elements and solutions

- Ensure project delivery within deadlines while maintaining exceptional front-end performance standards

- Break down complex performance challenges into manageable tasks

- Develop and maintain performance checklists and best practices

- Provide technical leadership in internal and client meetings to resolve performance challenges

- Deliver precise time and resource estimates for implementation and optimisation initiatives

- Collaborate with Product, UX/UI, QA, and developers to ensure optimal performance across all components

- Maintain clear communication with clients and stakeholders regarding performance metrics and improvements

- Create POCs to trial new performance technologies and techniques

- Mentor other developers in performance best practices

- Write detailed performance specifications, strategies, and technical documentation

- Collaborate on solution architecture prioritising performance, scalability, and maintainability

- Monitor and analyse application performance, identifying and resolving bottlenecks

- Implement and maintain performance testing frameworks and monitoring solutions

- Liaise with migration teams to ensure performance during legacy CMS to DXP transitions

- Foster a collaborative and productive working relationship with the Agile Project Manager

- Provide constructive feedback to the Development Manager regarding team training needs and professional development opportunities

- Continuously assess and verify technical decisions and approaches