Mobile app design is a pivotal aspect of app development, with the user interface playing a critical role in user engagement, conversion rates, and revenue generation. Various tools facilitate the design process by enabling teams to create interactive prototypes and collaborate efficiently. Adobe XD offers robust prototyping capabilities within the Adobe ecosystem, while Axure allows for the creation of custom controls and supports team collaboration. Balsamiq provides a quick wireframing experience akin to sketching on a whiteboard, making it ideal for agile teams. Canva excels in early-stage visualization with its ease of use, while Figma offers real-time collaboration and advanced prototyping features. Fluid UI and Framer focus on creating visually engaging prototypes with interactive elements, and Justinmind provides comprehensive prototyping without coding. Marvel simplifies creating wireframes, and Miro integrates FreeHand's design features for collaborative workflows. Mockplus, OmniGraffle, and Origami Studio offer varying levels of interactivity and design capabilities. Penpot stands out for being open-source, Proto.io and ProtoPie excel in high-fidelity prototyping, with ProtoPie integrating device sensors for realistic interactions. Sketch is a macOS-specific tool focusing on design systems and collaboration, and UXPin allows for highly interactive and functional prototyping with its Merge technology, bridging the gap between design and code.