Senior Frontend Engineer

Senior Frontend Engineer
We build and operate Connect, a SaaS platform for the beauty & wellness industry that helps entrepreneurs run their businesses more effectively. Our web products are used daily by tens of thousands of people across 13 European countries.
Our teams own their areas from initial idea and design through deployment and operations. We focus on writing maintainable, scalable code while balancing legacy and modern technologies. We encourage engineers to experiment with new ideas, learn from mistakes, and improve our systems continuously.

You will be responsible for:

• Take ownership of the frontend experience from design to deployment to operations.
• Pair with engineers, designers, and PMs to ship features every cycle, iterating based on real usage and feedback.
• Participate in design and code discussions, making trade-offs and decisions that affect the product and the team.
• Maintain a strong focus on automated testing, applying the testing pyramid to ensure unit, integration, and end-to-end coverage.
• Improve our frontend observability by adding metrics, dashboards, and alerts with tools like Datadog, Sentry, and web vitals to catch issues before they impact users.
• Be an active part of the Frontend Guild, collaborating with other engineers to share ideas, improve standards, and tackle cross-team frontend challenges.
• Lead technical discussions about trade-offs in features, architecture, and UX, helping the team make informed decisions that balance product goals and engineering constraints.
• Navigate a hybrid codebase, balancing work between legacy systems and modern React/TypeScript.

Our frontend stack:

The frontend stack is a mix of legacy and modern technologies. The application originally grew as a Backbone-based product, served through Node/Express with EJS templates, and there are still important areas of the product that work this way today. At the same time, the team is actively migrating the frontend toward a more modern React and TypeScript architecture, delivered into the existing application through a gradual, page-by-page and feature-by-feature transition.

In practice, that means most new development now happens in the modern React/TypeScript stack, using tools and patterns such as React Query, Storybook, Jest, and Cypress, while some work still involves the legacy Backbone codebase and the integration layer between old and new parts of the app. 

We’re looking for someone comfortable with modern frameworks, but pragmatic enough to navigate an evolving codebase. In this role, you’ll help drive the frontend forward, working across a variety of problems and technologies.
About you:

• 7+ years of software development experience, with a strong focus on modern web frontend technologies.
• You take responsibility for the code you write and the areas you own, spotting bugs, performance issues, or UX gaps, and fixing them proactively without waiting for direction.
• You have a product mindset - you think about the person using what you build, ask why before how, and push back when something doesn't make sense
• You actively leverage AI tools in your daily development workflow, viewing them as force multipliers for productivity, code quality, and problem-solving.
• Excellent English communication skills - you can articulate complex technical ideas clearly to engineers, designers, and non-technical stakeholders.
• Sharp product thinking and a focus on UX, paying attention to the little things - edge cases, empty states, error handling.
• You are comfortable working with remote and co-located teams to deliver results.
• Structured, analytical, and highly collaborative, particularly in a remote context.

Nice to haves

• Frontend observability experience (Datadog, error tracking, monitoring, performance metrics, web vitals).
• Experience with mobile-first design, atomic design principles, design systems, and progressive enhancement for responsive applications.
• Full-stack mindset: you may not have actively written backend code, but you understand key architectural principles such as event-driven architectures, caching strategies, eventual consistency and how frontend and backend communicate effectively.
• You’ve experimented with various forms of AI in product development and have opinions about where it could make products or workflows better.

About Treatwell

Hi, we’re Treatwell. Nice to meet you.

We’re a team of 700 passionate and brilliantly talented people across Europe. We’re the industry’s smartest salon management software, all connected to Europe’s leading bookings platform, working with over 50,000 salon partners across 13 countries, processing over 8 million bookings every month. And….breathe.

But we’re not done yet. We’re on an exciting journey to digitally revolutionise the hair and beauty community.

If this excites you, we might just have the role for you.
We’ll treat you with:

• 28 working days holiday, plus local bank holidays
• Monthly £/€40 Treatwell vouchers so you can treat yourself too
• Mental health support through our partnership with Open-Up
• Market-specific benefits that will be discussed in the interview process

Equal Ops

We are committed to fostering a diverse, inclusive, and equitable workplace and are proud to be an equal opportunity employer. All qualified applicants will receive consideration without regard to their condition.