Worked on the SciCatProject/scicat-backend-next repository to deliver robust conditional update functionality for backend APIs. Focused on implementing support for the If-Unmodified-Since HTTP header across multiple controllers, this work ensured that update operations only proceed if the resource has not been modified since the specified timestamp, thereby preventing concurrent modification issues and strengthening data integrity. Leveraged TypeScript and NestJS to integrate these changes at the controller level, aligning update logic with resource state and HTTP semantics. Emphasized thorough testing and backend development practices to ensure reliability and maintainability of the new feature within the existing codebase.