This deliverable outlines the functional and technical specifications of the VeriFish Mobile App, designed to support transparent communication about sustainable seafood choices. It builds upon the sustainability indicator framework developed in WP2 and responds directly to the project's mission of enabling citizens, producers, retailers, and stakeholders across the seafood value chain to make informed consumption decisions. The VeriFish Mobile App translates complex datasets into an accessible digital product, integrating data on nutrition, sustainability, biodiversity, and provenance. The design of the application is user-centric, informed by mock-ups and requirements gathered through a series of stakeholder workshops. The Mobile App will serve as an intuitive front-end to the underlying VeriFish Knowledge Base (KB), presenting FAIR data from sources such as GRSF, FishBase, and EuroFIR within a unified interface. Users will primarily access the system through existing GRSF QR codes, which serve as unique identifiers (UUIDs), enabling seamless linkage between stock-level information and value-added content such as food composition, recipes, and sustainability scores. Ultimately, the Mobile App will be one of the core media products of VeriFish, serving as a flagship tool for engaging a broad range of user groups—from informed consumers to seafood retailers—with verifiable, actionable knowledge. This document details the system architecture, key components, APIs, data flows, and user interaction models.