Senior Frontend Developer H/F - Flexcity

Are you passionate about energy, sustainability, and technology, with a drive to create impactful backend solutions?

Flexcity, a leading European energy tech company within the Veolia Group is looking for a resourceful Senior Frontend Developer to join our French team.

This position offers the opportunity to join the Flexcity R&D team in France, alongside a team of skilled colleagues from different backgrounds, within the company headquarters in Brussels.

At Flexcity, Tech is not a support function - IT is a key business driver. We operate in a complex, real-time, and highly regulated environment, requiring robust, secure, and adaptable systems to manage the increasing volatility of energy markets.Role

As a Senior Frontend Developer you will play a pivotal role in crafting and elevating our user interfaces and web applications. You'll drive feature development while ensuring code excellence through thorough reviews and mentoring junior developers. Working closely with cross-functional teams, you'll contribute to our technical strategy and deliver robust, scalable frontend solutions that empower our platform to manage real-time energy flexibility across Europe.

You will BE part of our tech team, under the UI Team Manager, and your role is divided in :
- Feature development & delivery - 60%

- Implement complex UI features in React/TypeScript
- Collaborate with product teams
- Own user-facing experiences from idea to release
- Evaluate technical feasibility
- Align with backend teams
- Quality, reviews & mentorship - 30%

- Conduct in-depth code reviews
- Ensure architectural consistency
- Uphold best practices in performance, accessibility, and typing
- Pair programming and guiding mid/junior engineers
- Onboarding new developers
- Write or maintain internal documentation and ADRs
- Tech strategy & cross functional collaboration - 10%

- Design scalable UI architecture
- Enforce frontend patterns
- Lead structural refactors
- Improve build tools, linting, and CI pipelines
- Contribute to roadmap decisions
- Contribute to component documentation / mockups (Figma, Storybook)

Hard Skills

Must Have
- Fluent in English and French
- Strong front-end development expertise
- Testing proficiency
- Architecture principles
- Component libraries & design systems
- Tooling & DX expertise

Nice to have
- UX sensibility
- DDD / Hexagonal Architecture
- Observability

Soft Skills
- Strong communication skills
- Leadership Skills
- Mentoring and knowledge sharing
- Problem-solving mindset
- Stakeholder management
- Meticulous attention to detail
- Product-oriented thinking