I was developing back-end for the DFM-IT application which stands for Digital Finance Modeling of IT infrastructure expenditures. - Developed 2 brand new crucial services concerning ways of modeling expenditures. The present functionality allowed to model using graph only. My develoment added the ability to model using table and another kind of graph. Thereby, the number of tools was increased by 3 times.- Designed expandable infrastructure for uploading and parsing Excel files which allows to add new parser anytime it is required. It led to development speed increase and eased existing code support.- Developed the number of services working asynchronously using Spring scheduling tasks. The services are targeted on performing tasks too expensinve for real-time working- Implemented user actions history which allowed to return to previous step while modeling expenditures- Significantly expanded reporting tools. It allowed to minimize data descrepancy between the app and other bank servides- Designed REST API with diverse data validation, documenting using Swagger editor and OpenAPIspecification- Wrote integration tests for new features and existing features' improvements- Improved legacy code parts with refactoring, reuse of code and following OOP principles- Did code reviews- Held the responsibility for development process and coordinated team work during team leadvacation