Math Circle Mate is a free, browser-based math practice application for K-12 students, offering 124 structured lessons across 4 learning tracks (grades 1-12). It uses a Duolingo-style interactive card interface with instant feedback and Socratic hints that guide students to think rather than just get answers. The app is bilingual (English and Chinese), requires no account for the first 5 lessons of each track, and offers one-time $3 lifetime access for the full curriculum.