The development of accessible interfaces for autistic people requires specialized knowledge and structured processes that are often scattered across literature. This work presents GuideAut, a web platform that provides access to the ProAut process—a structured methodology for prototyping application interfaces for autistic users. GuideAut not only offers access to the phases and activities of ProAut but also provides automated tools for generating essential Human-Computer Interaction artifacts, such as personas (PersonAut) and empathy maps (EmpathyAut), as well as a repository of collaborative recommendations. The platform was evaluated by 14 participants using the Technology Acceptance Model (TAM), showing excellent results in terms of perceived usefulness (86.7%) and ease of use (80%). The results indicate that GuideAut effectively supports interface designers and developers in creating more inclusive applications for autistic users, while also highlighting areas for improvement in user experience and mobile responsiveness.