We are building a web application where users can upload PDF files into folders and manage them. The project is mostly developed (frontend and backend are already in place), but it is currently not working end-to-end due to deployment and integration issues. The main requirement is to fix the existing system and make the complete flow work properly in production. This includes ensuring that the backend API is correctly deployed, all routes are active, and the file upload functionality works as expected. The expected working flow is: User uploads a file → file is stored on the server → file details are saved in the database → API returns a proper response → file appears in the frontend UI → file remains available after refresh. In addition to fixing the upload flow, the system should be stabilised so that there are no broken states, loading issues, or API mismatches between frontend and backend. Once the upload flow is fixed, the next requirement is to implement a basic document viewer so that users can open and view the uploaded PDF files within the application. We are not building from scratch. The project is already developed to a large extent, so the task is mainly to understand the existing codebase, fix deployment issues, complete the integration, and ensure the system works smoothly on the live server. We are looking for someone who can take ownership of the project, quickly identify the issues, and deliver a stable and fully working solution.