The Level should be Middle to Senior.
Additionally, the dev should be ready to work with an existing project, understand it.
Starting hours scope is from 20 to 30 with possible future scope extension.
The tasks are:
Add API and logic for new functionality.
Tight collaboration with front-end developers.
Change existing API endpoints according to changes in DB ( f.e. add new fields, change field type, change sorting, etc.)
Implement API based on stored functions.
Move from one API version to new one.
Debug and troubleshoot the App.
Spring Boot, PostgreSQL, Java 8 to 11.