Senior Fullstack Software Architect (freelance contract)

Senior Fullstack Software Architect (freelance - 12-month minimum contract) At Sunstice , we are undertaking a major transformation of our applications to improve scalability, maintainability, and overall software quality. As part of this initiative, we are looking for a Senior Fullstack Software Architect to join our team on a 12-month freelance contract (minimum) and contribute to key modernization projects. About the Role You will join an agile team working on strategic initiatives focused on reducing technical debt, evolving our software architecture, and modernizing our frontend applications. As a senior engineer, you will play an active role in technical decision-making while contributing hands-on throughout the software development lifecycle. What You Will Do As a Software Architect, you will: Analyze and assess the existing technical debt, identifying opportunities for improvement. Refactor and decompose complex application modules. Drive the migration from a monolithic application to a microservices architecture. Contribute to the migration of the frontend from Vanilla JavaScript to React. Design and implement deployment pipelines and continuous integration practices. Participate in all phases of software development, including technical analysis, design, implementation, automated testing, code reviews, and continuous improvement. Collaborate closely with developers, architects, and product stakeholders to deliver scalable and maintainable solutions. Help define technical solutions that address architectural, performance, and business challenges. Technology Stack Backend: Java, Spring Boot Frontend: React, Vanilla JavaScript Architecture: Microservices Development Practices: TDD Containerization: Docker Version Control: GitHub Who We Are Looking For We're looking for an experienced software architect with: At least 8 years of professional software development experience . Proven experience delivering application modernization, migration, or large-scale refactoring projects. Strong expertise in Java and microservices-based architectures. Hands-on experience migrating frontend applications from Vanilla JavaScript to React. Solid understanding of modern software engineering practices, including TDD, CI/CD, and code reviews. Experience with application performance optimization and software architecture is highly valued. The ability to work autonomously while collaborating effectively within cross-functional teams. Strong analytical skills, a pragmatic mindset, and a passion for solving complex technical challenges. Département Research & Development Locations HQ France Remote status Hybrid