Full Stack Developer

About Us We are a French company specializing in the development and operation of critical computing infrastructures, with a focus on hyperdense data centers dedicated to artificial intelligence.

Sesterce was built on a clear conviction: Europe needs sovereign, high-performance, and decarbonized AI infrastructure. In full growth mode, our mission is to design, build, and operate next-generation computing campuses across France and internationally. Our solutions power the most demanding AI workloads for leading clients in the industry. To strengthen our Engineering team, we are looking for a versatile, quality-driven, and collaborative Full Stack Developer.

Your Responsibilities Frontend Development Build modern, responsive, and accessible UIs with Next.js and React.js

Implement UI components in collaboration with UX/UI designers (Figma, Storybook)

Optimize front-end performance (Core Web Vitals, lazy loading, code splitting, SSR/SSG)

Write frontend tests (Jest, React Testing Library, Cypress) Backend Development Design and build RESTful APIs and backend services with Node.js

Model and manage databases (MongoDB, MySQL, PostgreSQL)

Implement authentication and authorization (JWT, OAuth 2.0)

Secure APIs (input validation, rate limiting, error handling, logging)

Build integrations with third-party systems (monitoring APIs, business tools) Architecture & Quality Write clean, maintainable code following SOLID principles and proven design patterns

Conduct constructive code reviews and participate actively in pull request processes

Optimize applications for speed, scalability, and resilience

Write technical documentation (API docs, architecture guides, READMEs) Product & Collaboration Participate in sprint planning and backlog refinement

Collaborate closely with product, design, infrastructure, and ops teams

Monitor application performance in production Your Profile Education & Experience Bachelor's in Computer Science or equivalent

Proven Full Stack experience with Node.js and Next.js Technical Skills Proficient: JavaScript/TypeScript, HTML, CSS, React.js, Next.js, Node.js

Databases: MongoDB, MySQL, PostgreSQL

RESTful API design and Git (branching, PR workflows)

Testing tools (Jest, Cypress) are a plus

Blockchain/Web3 experience is a plus Personal Qualities Quality-driven with a strong sense of ownership

Collaborative, communicative, and comfortable in an agile environment Languages English: professional level required

French: a plus Why Join Us? Build the web platform that powers Sesterce's GPU infrastructure and client experience

Work end-to-end across the full stack: from pixel-perfect UIs to robust backend APIs

Ship in a fast-moving startup where your code is in production and makes a real difference A tight-knit, demanding, and passionate team where every contribution matters

Competitive package: salary based on profile, health insurance, transportation How to Apply Send your application (resume + cover letter) to: hr@sesterce.com

Please use the reference "DEV-FS-MRS" in the subject line of your email.