We are seeking a **Senior Server\-side Engineer** to build the Mobile application Service Layer used by millions worldwide. You will work on the Mobile application Service Layer (Backend for Frontend) consumed by award\-winning mobile apps, collaborating with a large team of engineers, product people, designers, and QA. This role requires strong technical skills, creativity, and a passion for solving challenging problems with modern technologies. If you enjoy sharing your ideas and care deeply about user experience and beautiful code, we encourage you to apply. **Responsibilities** * Build server\-side applications for the mobile service layer * Write clean, efficient, and maintainable code * Refactor legacy code to improve performance and readability * Delete obsolete code to streamline the codebase * Develop and maintain build tools and continuous integration processes * Fix bugs and troubleshoot production issues * Implement asynchronous code for better performance * Analyze and optimize application performance * Create and maintain unit tests to ensure code quality * Collaborate with a cross\-functional team including product, design, and QA * Integrate with bespoke backend services * Design solutions for open\-ended problems * Contribute to open source projects within the team **Requirements** * Bachelor’s degree in Computer Science or a related field, or equivalent experience * Strong experience with algorithms and data structures with 3\+ years in server\-side development * Proficiency in REST API design and implementation * Hands\-on experience with Spring Boot framework * Experience writing unit tests and test\-driven development * Knowledge of asynchronous programming and performance optimization * Ability to work effectively in a team environment * Self\-starting attitude with strong problem\-solving skills * Experience with legacy code refactoring and maintenance * Proficiency in English language, level B2 (Upper\-Intermediate) **Nice to have** * Experience with Docker containerization * Familiarity with Gradle build automation * Knowledge of GraphQL APIs * Proficiency in Kotlin programming language * Experience with RAML API modeling