Senior/Lead Java Developer at Synechron, London, £Contract Rate

Senior/Lead Java Developer

About Synechron:

Synechron is a leading digital transformation consulting firm dedicated to delivering innovative technology solutions within banking, financial services, and insurance. We thrive on engineering excellence, collaboration, and a passion for cutting-edge technologies.

We are seeking a highly skilled and experienced Senior/Lead Java Developer with 10+ years of hands-on experience in enterprise application development. The ideal candidate must possess strong expertise in core Java fundamentals, concurrency, and distributed systems, along with exposure to AI/ML-driven solutions.

This role demands a deep understanding of data structures, system design, performance optimization, and scalable architecture, along with the ability to lead technical initiatives and mentor teams.

This role is Inside IR35 contract

Job Location: London (Hybrid - 3 days in the office)

Key Responsibilities:

• Design, develop, and maintain high-performance, scalable Java-based Back End systems

• Architect and implement microservices-based and distributed applications

• Develop and optimize data structures and algorithms in real-world use cases

• Ensure correct and efficient usage of collections (eg, HashMap internals, hashing, collision handling)

• Implement and review robust object contracts (hashCode() and equals()

• Design and manage concurrency and synchronization mechanisms, including:

• Thread safety

• Object-level vs class-level locking

• Implement locking strategies:

• Optimistic and pessimistic locking

• Distributed locking (eg, Redis/Zookeeper-based solutions)

• Design solutions for caching, de-duplication, and performance optimization in large-scale systems

• Build and maintain RESTful APIs and event-driven systems (Kafka/RabbitMQ)

• Collaborate with data scientists/AI engineers to integrate ML/AI models into Back End systems

• Contribute to system design discussions, code reviews, and technical mentoring

• Ensure performance, reliability, scalability, and security of applications

• Drive adoption of best practices in CI/CD, DevOps, and cloud-native development

Required Technical Skills

Core Java & Backend Development

• 10+ years of experience in Java (Java 8+)

• Strong expertise in:

• Collections framework (deep understanding of HashMap, hashing, collisions)

• Memory management and JVM behavior

• Multithreading and concurrency

• Strong understanding of:

• hashCode() and equals() contract and implications

• Performance impact of poor hashing strategies

Concurrency & System Design

• In-depth knowledge of:

• Thread synchronization and locking mechanisms

• Object-level vs class-level locking

• Race conditions and thread safety

• Strong understanding of:

• Optimistic vs pessimistic locking (use cases and trade-offs)

• Distributed locking patterns

• Experience designing:

• Highly scalable, fault-tolerant distributed systems

Distributed Systems & Performance

• Strong experience in:

• Microservices architecture

• API design and integration

• Hands-on expertise in:

• Caching strategies (Redis, Ehcache, etc.)

• De-duplication mechanisms and idempotent processing

• Ability to troubleshoot performance bottlenecks and scalability issues

AI/Machine Learning Exposure (Preferred)

• Experience integrating AI/ML models into Back End systems

• Understanding of:

• Model life cycle, inference, and deployment

• Familiarity with:

• Generative AI/LLMs (OpenAI, Azure OpenAI, Hugging Face, LangChain)

• Python ML frameworks (basic integration level: TensorFlow, PyTorch, Scikit-learn)

Cloud & DevOps

• Experience with cloud platforms (AWS/Azure/GCP)

• Hands-on experience with:

• Docker, Kubernetes

• CI/CD tools (Jenkins, GitHub Actions, GitLab CI)

• Understanding of cloud-native architecture and scaling patterns

Leadership & Soft Skills

• Ability to lead technical design discussions and architecture decisions

• Strong problem-solving and analytical skills

• Experience in mentoring and guiding junior developers

• Effective communication with cross-functional teams

Diversity Statement

Synechron are proud to be an equal opportunity employer. Our Diversity, Equity, and Inclusion (DEI) initiative Same Difference' is committed to fostering an inclusive culture - promoting equality, diversity and an environment that is respectful to all. We encourage applicants from across diverse backgrounds, race, ethnicities, religion, age, marital status, gender, sexual orientations, or disabilities to apply. We offer flexible workplace arrangements, mentoring, internal mobility, learning and development programmes to support our global workforce. Empowerment and collaboration are at the core of how we operate.

All employment decisions at Synechron are based on business needs, job requirements and individual qualifications, without regard to the applicant's gender, gender identity, sexual orientation, race, ethnicity, disabled or veteran status, or any other characteristic protected by law.