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. Take ownership of the frontend experience from design to deployment to operations.
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. 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.
7+ years of software development experience, with a strong focus on modern web frontend technologies.
~ You take responsibility for the code you

📌 Senior UX Engineer/Front-End Engineer (Madrid)
🏢 Treatwell
📍 Madrid