-KEDADRA ,SelmaLECHEHEB ,NaimaALI GUECHI ,Farida2026-11-022026-11-022026http://dspace.univ-skikda.dz:4000/handle/123456789/6538Cloud Computing and Blockchain are two key technologies in modern information systems. While Cloud Computing provides scalable and flexible resources for data storage and processing, Blockchain offers a decentralized and secure environment that ensures data integrity and transparency. This dissertation presents a comparative study between the two technologies with a focus on security aspects. A practical application was developed using MongoDB Atlas and BigchainDB to evaluate their performance and security. The results show that Cloud Computing offers greater flexibility and efficiency, whereas Blockchain provides enhanced mechanisms for ensuring data integrity, traceability, and transparency. The study highlights the strengths and limitations of both technologies and demonstrates their potential contribution to building secure and reliable information systems.enThesis