Senior Fullstack Software Architect (freelance contract)

Sunstice; France; Sur place; EUR 100 000 - 140 000; Plein temps

Résumé du poste

Sunstice is undergoing a major modernization of its applications. We seek a Senior Fullstack Software Architect to lead technical modernization on a 12-month freelance contract.

You will guide architecture, oversee refactoring, and drive migration from a monolith to microservices, while transitioning frontend from Vanilla JS to React. You will participate in all lifecycle stages, design deployment pipelines, and work autonomously within an agile team to deliver scalable, high-quality software

Qualifications

• 8+ years of professional software development experience.
• Experience delivering modernization or large-scale refactoring projects.
• Strong expertise in Java and microservices-based architectures.
• Hands-on frontend migration from Vanilla JavaScript to React.
• Familiarity with TDD, CI/CD, and code reviews.
• Ability to work autonomously within cross-functional teams.

Responsabilités

• Analyze and assess 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.

Connaissances

Java

Microservices

React

Vanilla JavaScript

TDD

CI/CD

Docker

GitHub

Software architecture

Autonomy

Outils

GitHub

Description du poste

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

• 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.