AgileEngine is an Inc. 5000 company that creates award-winning software for Fortune 500 brands and trailblazing startups across 17 industries. We rank among the leaders in areas like application development and AI/ML, and our people-first culture has earned us multiple Best Place to Work awards. WHY JOIN US If you're looking for a place to grow, make an impact, and work with people who care, we'd love to meet you! ABOUT THE ROLE As a Senior Backend Engineer, you will design and optimize high-performance, multi-threaded systems, transforming legacy workflows into scalable, thread-safe architectures. Leveraging deep expertise in C#, SQL, and AWS, you’ll drive concurrency improvements, enhance system throughput, and support large-scale data processing with technologies like Apache Spark. This role offers strong technical ownership and the opportunity to shape reliable, high-impact backend systems in complex environments. WHAT YOU WILL DO - Lead the design and development of highly concurrent, multi-threaded applications in C#; - Re-architect legacy synchronous workflows into scalable, thread-safe solutions; - Apply advanced knowledge of threading models, synchronization primitives, and performance tuning to optimize system throughput and minimize contention; - Design, develop, and optimize complex SQL queries, stored procedures, and large-scale data operations; - Utilize Apache Spark for distributed data processing at scale; - Deploy and manage solutions on AWS, ensuring reliability, scalability, and cost efficiency; - Diagnose and resolve concurrency issues, perform application profiling, and drive continuous improvements in system performance; - Collaborate with cross-functional teams to define technical requirements, align architecture with business goals, and deliver high-quality solutions. MUST HAVES - 4 years of experience as a software engineer; - Expert-level proficiency in C# with experience in multi-threaded and parallel processing; - Understanding of C++ ; - Strong understanding of threading models, synchronization primitives, and concurrency debugging ; - Proven experience in performance tuning and application profiling for large-scale systems; - Advanced proficiency in SQL ; - Proven experience deploying solutions on AWS ; - Strong problem-solving and debugging skills focused on scalability and reliability; - Upper-intermediate English level. NICE TO HAVES - Hands-on experience with Apache Spark; - Experience in re-engineering legacy systems into modern architectures; - Familiarity with microservices design principles and cloud-native development patterns; - Strong communication and collaboration skills with cross-functional teams. PERKS AND BENEFITS - Professional growth: Mentorship, TechTalks, and personalized growth roadmaps. - Competitive compensation: USD-based pay with education, fitness, and team activity budgets. - Exciting projects: Modern solutions with Fortune 500 and top product companies. - Flextime: Flexible schedule with remote and office options.