**Join us and receive a $2,500 sign\-on bonus!** **Important:** *after confirming your application on this platform, you’ll receive an email with the next step: completing your application on our internal site, LaunchPod. So keep an eye on your inbox and don’t miss this step — without it, the process can’t move forward.* **About the role** As a **Senior/Lead C\# Backend Engineer** at AgileEngine, you will lead the modernization of our core systems by designing and developing highly concurrent, thread\-safe applications. You’ll optimize large\-scale data operations, leverage distributed processing with Apache Spark, and deploy scalable solutions on AWS, driving performance, reliability, and scalability across our platforms. **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, including staging and transformations; * 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** * **5\+ years of expert\-level proficiency in C\#** with hands\-on experience in multi\-threaded and parallel processing; * 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** (query design, optimization, and data operations); * Hands\-on experience with **Apache Spark** for distributed data processing; * Proven experience deploying solutions on **AWS**; * Exceptional problem\-solving and debugging skills with a strong focus on scalability and reliability; * Upper\-Intermediare English level. **Nice to haves** * 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 a track record of working in cross\-functional teams. **About us** 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. If you're looking for a place to grow, make an impact, and work with people who care, we'd love to meet you! **Perks and benefits** * **Professional growth:** Accelerate your professional journey with mentorship, TechTalks, and personalized growth roadmaps. * **Competitive compensation:** We match your ever\-growing skills, talent, and contributions with competitive USD\-based compensation and budgets for education, fitness, and team activities. * **A selection of exciting projects:** Join projects with modern solutions development and top\-tier clients that include Fortune 500 enterprises and leading product brands. * **Flextime:** Tailor your schedule for an optimal work\-life balance, by having the options of working from home and going to the office, whatever makes you the happiest and most productive. Job Type: Full\-time Work Location: Remote