Senior Java Developer – Spring Boot, Microservices & Multithreading (W2 ONLY)

About the role

Location: Englewood Cliffs, NJ. Duration: Long‑Term, Ongoing Contract. Experience: 8+ Years. Position Type: Contract. Work Arrangement: Hybrid – 3 days a week onsite.

Responsibilities

• Design, develop, and maintain high-performance backend applications using Java and Spring Boot.
• Build scalable, resilient microservices and RESTful APIs.
• Develop and optimize multithreaded and concurrent Java applications.
• Implement efficient asynchronous processing and parallel execution mechanisms.
• Design backend services capable of processing large volumes of data with low latency and high throughput.
• Apply distributed systems principles to ensure application scalability, reliability, and fault tolerance.
• Optimize application performance, memory utilization, JVM behavior, and database interactions.
• Troubleshoot complex production issues involving concurrency, thread contention, memory leaks, and performance bottlenecks.
• Collaborate with architects, engineering teams, and business stakeholders to translate requirements into robust technical solutions.
• Participate in architecture discussions, technical design reviews, and code reviews.
• Write clean, maintainable, well-tested production-quality code.

Requirements

8+ years of professional Java development experience; strong hands‑on experience with Java 11/17/21 or newer; excellent understanding of Java collections, generics, streams, and functional programming; deep knowledge of multithreading, concurrency, synchronization, and thread safety; experience with ExecutorService, CompletableFuture, thread pools, concurrent collections, and asynchronous programming; strong understanding of JVM internals, garbage collection, memory management, and performance tuning.

Extensive hands‑on experience with Spring Boot and the Spring ecosystem; proven experience designing and developing microservices‑based applications; strong knowledge of REST APIs, service‑to‑service communication, and API design; understanding of distributed transactions, resilience patterns, circuit breakers, retries, and fault tolerance; experience building scalable, highly available backend services.

Experience developing high‑throughput, low‑latency applications; strong understanding of concurrent processing, asynchronous workflows, and event‑driven architectures; ability to identify and resolve performance bottlenecks; experience with distributed caching, messaging, and data processing systems; strong debugging, profiling, and production troubleshooting skills.

Strong SQL skills and experience with relational databases such as PostgreSQL, Oracle, or MySQL; experience with database query optimization and performance tuning; proficiency with Git, Maven/Gradle, and automated testing frameworks; experience with CI/CD pipelines and modern software engineering practices.

This is a hands‑on senior engineering position, not primarily a team management or coordination role. The successful candidate should be comfortable writing complex Java code independently, designing and troubleshooting multithreaded applications, explaining concurrency concepts and their practical implementation, building production‑grade Spring Boot microservices, solving complex performance and scalability challenges, understanding architectural trade‑offs in distributed systems, and taking technical ownership of backend components from design through production.

Preferred Skills

• Experience with market data, financial data, real‑time data feeds, or other data‑intensive platforms.
• Hands‑on experience with Kafka or similar event‑streaming technologies.
• Experience with Redis or other distributed caching solutions.
• Familiarity with