Proto.io

Proto.io is a web-based tool for creating interactive, high-fidelity app prototypes without coding. Designers can drag in prebuilt UI kits for iOS, Android, or web. Animations, gestures, and transitions mimic real app experiences. Built-in collaboration allows reviewers to comment on specific screens or elements. A usability testing feature gathers user interactions. Integrations with popular design tools (Sketch, Figma) streamline workflow. Proto.io’s free trial and tiered pricing help freelancers or agencies validate mobile or web app flows, ensuring the final product meets user expectations before development.