Senior Java Engineer

Company Overview & Vision

Founded in Singapore in April 2026, CITA Lab is a dynamic software development startup dedicated to building high-quality, custom blockchain-related products tailored specifically to our customers' requirements. Our diverse product lineup includes centralized/decentralized cryptocurrency exchange solutions, secure crypto wallets, smart contracts, dApps, and more. We turn complex blockchain capabilities into seamless, secure, and intuitive user experiences for clients worldwide.

What You'll Do

As a Senior Java Engineer at CITA Lab, you will play a key role in designing and developing backend services for crypto exchanges, wallets, payment systems, digital asset platforms, and blockchain infrastructure.

You will work on systems where performance, reliability, security, concurrency, and financial correctness are critical.

This is not just an implementation-focused role. We expect Senior Engineers to participate in system architecture, technical decision-making, code reviews, production troubleshooting, performance optimization, and engineering standards.

You'll collaborate closely with Backend Engineers, Blockchain Engineers, Database Engineers, DevOps/SRE Engineers, Security Engineers, and Solution Architects.

Responsibilities

• Design, develop, and maintain high-performance backend services using Java and the Spring ecosystem.
• Build scalable backend architecture for crypto exchanges, wallets, payment systems, and digital asset platforms.
• Design reliable APIs and internal services for high-volume transactional workloads.
• Develop systems handling financial operations such as balances, deposits, withdrawals, transfers, settlements, and transaction histories.
• Design and implement highly concurrent and distributed backend systems.
• Ensure correctness and consistency when processing financial transactions.
• Build resilient integrations with blockchain nodes, wallet infrastructure, external financial services, and third-party APIs.
• Design asynchronous and event-driven systems using technologies such as Kafka.
• Optimize application performance, latency, throughput, memory utilization, and JVM behavior.
• Design reliable retry, idempotency, timeout, and failure-recovery mechanisms.
• Work with relational and NoSQL databases and help define appropriate data models and transaction boundaries.
• Participate in architecture discussions and technical design reviews.
• Write clean, maintainable, well-tested production code.
• Perform code reviews and establish backend engineering best practices.
• Troubleshoot complex production issues and participate in root-cause analysis.
• Improve monitoring, logging, tracing, and overall system observability.
• Mentor other engineers and contribute to the technical growth of the engineering team.

Requirements

• 5+ years of professional software engineering experience, with significant backend development experience using Java.
• Strong proficiency in Java 11/17/21+ and modern Java development practices.
• Strong production experience with Spring Boot and the broader Spring ecosystem.
• Deep understanding of Java concurrency, multithreading, synchronization, thread pools, and asynchronous programming.
• Strong understanding of JVM internals, memory management, garbage collection, and performance tuning.
• Experience designing and operating distributed systems and microservice architectures.
• Strong understanding of RESTful API design and service-to-service communication.
• Experience with relational databases such as PostgreSQL or MySQL.
• Strong knowledge of transactions, isolation levels, locking, concurrency control, and database consistency.
• Experience with Redis or similar distributed caching technologies.
• Experience with message brokers or event-streaming platforms such as Kafka.
• Strong understanding of fault tolerance, retries, idempotency, timeouts, and distributed-system failure scenarios.
• Experience writing unit, integration, and end-to-end tests.
• Experience debugging and optimizing production systems.
• Strong understanding of Git-based development workflows and code review practices.

Nice-to-Have

• Cryptocurrency exchanges
• Blockchain infrastructure
• Crypto wallets or custody platforms
• FinTech
• Payment systems
• Banking systems
• Trading platforms
• Financial ledger systems
• High-frequency or low-latency systems
• High-volume transactional platforms

If you are ambitious and believe that digital assets could be the next financial and technological revolution, please apply!

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