With thousands of mobile applications submitted to online application stores the mobile application market has experienced a significant growth. This growth is however accompanied by an increase in malware presence which is detected after infecting users or when a it is reported to the store. A possible solution would be to leverage those reports, across all mobile ecosystem, creating a shared reputation system, to provide more accurate feedback to the app stores quality assurance and security teams. To support this sharable reputation management system, we present a scalable blockchain-based solution, that provides the necessary scalability, data privacy and trust requirements, while being cost-effective. This paper also presents a real case study and respective results on performance, scalability, and cost evaluation. case study and respective results on performance, scalability, and cost evaluation. MOBILE APPLICATIONS economy is an expanding market. In August 2019, Google Play Store had almost 2.5 million apps in its repositories, Apple App Store had 1.8 million and Aptoide with nearly 1 million, with 21.3 billion downloads in Google Play alone [1], with several other third-party app stores experiencing similar rates [2]. However, malware presence has also increased [3], which exposes users to possible privacy breaches and loss of assets (e.g., baking