Participate in Payment module, collaborate with domain experts to understand the business domain, develop RESTful APIs for initiating payments, checking and validating payment status. Write comprehensive unit tests, achieving over 80% code coverage, ensuring a clear and maintainable codebase.

Migrate a legacy geolocation processing system to microservices architecture, focusing on data collection and analyzing functions. Collaborate with clients to design RESTful APIs, ensuring they met business requirements and were scalable. Reduce execution time of long-running task from 2 hours to around 40 seconds by optimizing the algorithm and data processing. Increase request handling capacity from 200 to 500 requests per minute by implementing asynchronous programming using RxJava. Communicate effectively with clients, understand their needs, discuss progress, blockers and solutions. Work with frontend team to deliver complete solution to end user. Write unit tests using JUnit5 and BDDMockito, achiving 90% code coverage.

Design and implement a chatlog database (~40.000 messages/day). Monitor chatbot system quality, generate statistic reports to admin and client

Build a remote control system in car. Analyze customer requirements, create software requirement, also create high/low level design and implement them. Be responsible for a team of 3 members, plan workload, ensure team members stayed on tasks, deal and resolve client problems.