Senior Java Developer

About the Company

Optifly is a cutting-edge schedule optimisation software company revolutionising how airlines build and manage flight schedules. Our proprietary AI-driven optimiser helps airlines maximise efficiency, improve profitability, and streamline operations. We work with some of the world's leading low-cost carriers such as Ryanair and Wizz Air and are expanding our product suite. As a fully remote company with people based in Ireland, Poland, Greece, Serbia, Ukraine and Armenia for example, we operate across multiple EU time zones, fostering a highly collaborative, fast-paced, and innovative work environment. 

Overview 

We are seeking an elite-level Java enterprise developer, a true 10x coder, to tackle our most pressing backend challenges. This is a high-intensity, 3-month engagement (with potential for a full-time role), requiring 40+ hours per week of deep, autonomous work. 

Our backend has significant technical debt, leading to data inconsistencies and bugs that directly impact our customers, optimiser and overall product performance. While a full rewrite isn’t feasible at this stage, we need a highly skilled engineer who can navigate the legacy codebase, understand the business logic, and make continuous, meaningful improvements.

Key Responsibilities 

• Work closely with our Product Owners to understand the business logic and with our front-end and operations research team to ensure that data is stored and passed correctly to the optimiser ensuring that business logic is accurately reflected. 
• Take ownership and pride in your work. Complete thorough testing of all work, including unit tests, integration tests, and end-to-end validation using the application. 
• Deep dive into our existing Java enterprise codebase, identify weaknesses, and implement high-impact improvements without disrupting operations. 
• Resolve persistent data inconsistencies that affect our optimiser, ensuring accurate and reliable data flow. 
• Refactor and optimise critical backend components to improve performance, stability, and maintainability. 
• Operate with extreme autonomy, proactively solving problems and improving system reliability without requiring constant oversight. 
• Diagnose and fix complex bugs, ensuring that backend issues do not block product development. 
• Use tools available to speed up and improve code quality (ChatGPT) 

Must-Have Skills & Experience 

• Fluent English 
• 10+ years of Java enterprise and Springboot experience, with a track record of delivering mission-critical systems. 
• Deep expertise in high-performance backend development 
• Strong experience with legacy codebases, including understanding, debugging, and improving existing business logic. 
• Expertise in SQL and data management, ensuring seamless data integrity and flow. 
• Proven ability to fix deeply embedded bugs and resolve data inconsistencies in complex systems. 
• Ability to work independently at an extremely high level, making informed architectural and design decisions without constant input. 
• Experience working with scheduling/airlines/optimisation engines, operations research teams, or high-complexity algorithmic systems is a big plus. 

Work Expectations 

• 40+ hours per week, this is an intense, hands-on role requiring full commitment. 
• Fully remote, but you must be available to sync with the team as needed. 
• Expected to deliver measurable backend improvements within the first few weeks. 

Why This Role? 

• Mission-critical impact. Your work will directly fix the bottlenecks that hinder our optimiser and overall product. 
• High autonomy – No micromanagement, just complex problems that need solving. 
• Work with top-tier technical professionals – Collaborate with our Front-end and Operations Research teams to build a stronger, more reliable backend. 

How to Apply 

If you are a world-class Java engineer who thrives in high-stakes, high-autonomy environments, we want to hear from you. Apply with: 

• Your resume (highlighting relevant backend & enterprise experience) and availability to start. 
• A brief explanation of a time you improved a legacy system without rewriting it.