OpenNotas is an open-source note-taking application, cross-platform based on PWA, focusing on security and device synchronization. OpenNotas follows the philosophy of "simplicity in usage," catering to anyone who needs to quickly and reliably jot down their notes in text format. OpenNotas supports Markdown, utilizing open-source text editing tools that can easily be expanded with additional features and utilities. OpenNotas supports synchronization via an Adapter, along with security features based on the AES encryption algorithm. Note encryption is also supported using a similar encryption algorithm.