About the ProjectWe are looking for a Senior Java Backend Developer to join a team tasked with stabilizing and transforming a business-critical application. The current system is fragile and has many issues, so your role will involve reverse engineering, gaining a deep understanding of both the codebase and business processes, and driving modernization.This is a brownfield project – success requires strong technical expertise, architectural thinking, and the ability to navigate ambiguity while making the system robust and future-proof. Over time, you will help rethink the architecture, improve performance, refactor existing code, and define a sustainable technical foundation.Responsibilities Analyze and stabilize a fragile application with the support of a service team Reverse engineer existing components and business logic to gain a deep understanding of the system Optimize database queries, data access, and memory management for performance and scalability Identify and implement code refactoring opportunities to improve maintainability Rethink system architecture and recommend appropriate tools, frameworks, and approaches Collaborate with business stakeholders to ensure technical solutions align with business needs Work closely with the team to establish engineering best practices and architectural principles Requirements 5+ years of experience in Java backend development Experience working on brownfield projects Solid understanding of software architecture principles and system design Proven ability in reverse engineering, debugging, and stabilizing fragile systems Experience with databases, memory management, and large-scale data handling Skills in refactoring and improving code quality Ability to quickly learn and understand complex business processes Excellent communication skills and openness to working with international teams (US, India, PL) Nice to Have Experience with performance-critical enterprise applications Query tuning and performance optimization Knowledge of domain-driven design or other structured architectural approaches Familiarity with modernization strategies and enterprise integration tools Why Join This Project? Work on a high-impact application that is critical to business operations Opportunity to shape and modernize the architecture, not just maintain it Long-term potential with a multi-year modernization roadmap Collaborative international environment with challenging, meaningful problems to solve