Decision Mentor is a multi-criteria decision making application designed to simplify complex decision-making for both public and private contexts. The tool facilitates a problem-solving and critical thinking approach towards decision-making processes. It functions through an AI-driven, criteria-based process that allows users to identify preferred alternatives, prioritize their criteria, and compare options side by side, providing a visual representation of decisions. The compatibility with different user types, individuals, teams, or organizations, makes it versatile for various use-cases. Users' privacy is taken seriously; while information about personal decisions remains confidential, decisions opted public by users are shared in the public feed. Decision Mentor is underpinned by an Analytic Hierarchy Process (AHP), a Multiple Criteria Decision Making/Analysis (MCDM/MCDA) theory developed by Prof. Thomas L. Saaty. Furthermore, the tool integrates OpenAIs GPT-3.5 API for criterial suggestions, utilizing machine learning algorithms to analyze users' inputs and offer relevant advice. This application is suitable for users seeking aid in navigating complex choices or lacking advisory support on critical decisions.