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

**** W2 ONLY - NO C2C - NO VISA SPONSORSHIP AVAILABLE ****

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

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

About the Opportunity

We are seeking a highly skilled Senior Java Developer to join the engineering team of a leading media and technology organization.

The ideal candidate will have deep expertise in Core Java, Spring Boot, microservices architecture, multithreading, and high-performance backend application development .

This role involves designing, developing, and optimizing scalable, reliable, and high-throughput backend services supporting complex, data-intensive enterprise applications.

We are looking for a technically strong, hands-on engineer who understands Java internals, concurrent programming, distributed systems, and production-level performance optimization.

Key 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.

Required Technical Skills

Core Java & Concurrency

• 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.

Spring Boot & Microservices

• 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.

Performance & Distributed Systems

• 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.

Databases & Development Tools

• 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.

Preferred / Nice-to-Have 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 Kubernetes, Docker, and cloud platforms such as AWS.

• Experience with reactive programming frameworks.

• Understanding of messaging systems, event processing, and data ingestion pipelines.

• Experience building systems requiring high availability, low latency, and continuous data processing.

What We're Looking For

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.

• Taking technical ownership of backend components from design through production.

Candidates with strong Core Java fundamentals, practical multithreading experience, and deep Spring Boot/microservices expertise will be prioritized.