With the rapid evolution of cloud computing, individuals and organizations are managing data storage and collaboration in an entirely new way. Using blockchain technology, this paper introduces CloudShare, a new framework for sharing and collaborating across clouds using a secure, decentralized ecosystem. As a result of the proposed system, storage costs and upload bandwidth requirements are significantly reduced while data confidentiality and consistency are maintained. With CloudShare, you can encrypt and deduplicate data without relying on centralized authorities to protect your privacy. Simulated results demonstrate that the model is capable of optimizing resource utilization and efficiently securing sensitive data. A decentralized architectural model overcomes the limitations of traditional centralized cloud models, opening the door to innovative cloud computing applications.