Senior Frontend Engineer

About Welltech

About Welltech
Welltech is a global wellness technology company with Ukrainian roots. Our mission is to build and scale wellness apps globally through state-of-the-art, tech-driven performance marketing.
We are one of the most established players in the wellness app space, and we are accelerating. Over 25.5 million people across the world use our apps — Muscle Booster, Yoga-Go, and WalkFit — to build healthier habits, move more, and feel better every day. Every subscription represents a real person making a real change in their life, and we take that seriously.
With 500+ people across hubs in Cyprus, Ukraine, Poland, Spain, and the UK, we combine the scale of a market leader and the drive of a team that's just getting started.

Why join us?
Welltech is where your work reaches millions of real people.
We're looking for Well-Makers. You'll own decisions, outcomes, and the learning that comes with both. You'll move fast, because action beats perfection here. You'll say what you think, hear the truth back, and get better for it. And when the targets are big — and they are — you won't chase them alone.
If you want a job, there are easier places. If you want to go big — and do it together — this is it.

Position

We’re on the hunt for a Senior Frontend Engineer who’s ready to take ownership, lead with innovation, and build exceptional systems in the Monetization team - a core part of our Product Growth structure. If you're passionate about data-driven user journeys, experimentation, and highly optimized purchasing flows - this is something for you.

Our Monetization team maximizes user trust by creating seamless, transparent pricing experiences. We're a data-driven engine, constantly running experiments, refining strategies, and unlocking sustainable revenue growth. You'll work alongside experienced team members to evolve our monetization models and build products that matter - both for our users and our business.

Key responsibilities:

Collaborate across disciplines: Work closely with cross-functional teams including Frontend/Backend Engineers, QA, Product Analysts, and Product Managers to design, develop, and deliver innovative solutions that directly influence user experience and revenue. You won’t just ship code — you’ll shape how millions interact with our products. 

Engineer with purpose: Translate business requirements into performant, maintainable code that shapes user trust and monetization experience. 

Own your systems: Take responsibility for system performance, scalability, and data integrity. Spot issues before they happen and suggest smart fixes. Participate in monitoring (Sentry, Datadog).

Drive product and system evolution: Take initiative in shaping the future of our user identity and privacy systems. Audit what exists, identify areas for improvement, and lead the transformation of existing flows into modern, user-first solutions that unlock real value for both the company and our users.

Elevate the Standard: Be a champion of engineering excellence. Drive clean code practices, lead code reviews, mentor peers, and contribute to a culture of innovation. Share knowledge and bring strategic thinking into technical discussions.

Build with Best-in-Class Tech: Craft modern solutions using React 18+, React-Query, Styled Components, TypeScript 5+, and Vite. Help shape how we architect, deploy, and scale services used by a global user base. 

Your qualification

• Senior-level experience building and maintaining frontend applications in a product-first environment

• Mastery of JavaScript (ES6+) and TypeScript, with an eye for performance and maintainability

• Advanced knowledge of React and its ecosystem — you’re comfortable with Redux Saga, Core Web Vitals, and beyond

• A deep understanding of how the web works, including RESTful API integration, web security, and responsive UX patterns

• Solid grasp of software design principles — you live by SOLID and know how to apply design patterns pragmatically

• Experience implementing testing strategies

• Strong communication skills and fluent English (C1) — you're confident leading discussions and documenting decisions

• A passion for crafting delightful user experiences, and a mindset of continuous growth and learning

Will be a plus

• Experience working with experimentation platforms and running A/B or multivariate tests

• Experience with Material UI and its design philosophy

• Familiarity with Next.js, SSR, and performance optimization

• The confidence to set up or optimize bundler configs (Webpack/Vite) from scratch

What we offer

• Grow Together: Join a culture that champions both personal and professional growth. Here, you’ll thrive as we learn, evolve, and succeed together.

• Lead by Example: No matter your role, your leadership matters. Every team member is empowered to inspire and make an impact.

• Results-Driven: We’re all about achieving meaningful outcomes. It’s not just about the effort, but the difference we make every day.

• We Are Well-Makers: Be part of a movement that’s creating a healthier, happier world. Together, we make well-being a reality!

Additional details

Candidate journey: Recruiter call ----> Live Code Design Review --->  System Design Interview ----->  Meet the hiring manager

Check out some of our products

Muscle Booster — https://musclebooster.fitness/ 

Yoga-Go — https://yoga-go.io/ 

WalkFit - http://walkfit.pro