Healthtag is a platform that utilizes blockchain technology to decentralize healthcare data, empowering patients with full control over their health information. By shifting data ownership from centralized institutions to patients, it enhances transparency, security, and minimizes medical errors, including drug interactions. The platform incorporates various health data sources such as IoT, DNA, and telemedicine within a decentralized application (dApp). By adhering to HL7 FHIR standards, Healthtag facilitates the seamless transfer of data between healthcare systems, ultimately improving patient care, reducing treatment errors, and increasing healthcare service efficiency. Additionally, it supports public health planning, policy-making, and medical research, fostering cross-border health data exchange within ASEAN and worldwide. Healthtag aims to transform healthcare into a decentralized, connected system, enabling patients to easily access their health data while focusing on reducing suffering and improving treatment outcomes.