SecureSync: A Secure Cloud File Sharing Platform

Cloud-based file-sharing platforms are now integral to both professional and personal computing environments. Yet dominant solutions such as Google Drive and Dropbox demonstrate consistent deficiencies in user-level access accountability, time- bounded sharing, and resource governance at the application layer. This paper presents SecureSync, a secure cloud file-sharing platform built on AWS S3 and Java Spring Boot, integrating Clerk-issued JWT authentication, a credit-based upload governance mechanism, time-limited link expiry, and a write-only audit logging subsystem. The audit trail records all file operations with user identity, timestamp, and IP address, providing non- repudiation capabilities absent from mainstream platforms. The credit system introduces a novel per-upload resource constraint layer not addressed in prior literature. Implemented with React/Next.js on the frontend and MongoDB for persistence, SecureSync demonstrates that comprehensive security and accountability improvements can be achieved within a standard web application architecture without requiring cryptographic infrastructure or distributed ledger overhead.