Dictionary Diseases & Disorders — a large-scale Android medical reference app (4.5M+ downloads, 4.6★ rating) built with Kotlin (MVVM, Coroutines, Room) and powered by a Python backend (FastAPI, MongoDB, Celery, Redis). Key features: • Disease scanner — AI-powered image recognition of visible symptoms via camera or gallery • RAG-based LLM Q&A — users ask medical questions and receive context-aware answers from curated medical sources • Fuzzy full-text search — tolerant to typos and partial matches for better accessibility • Offline access with Room DB and cloud sync I led full-cycle development of both mobile and backend components, including AI/LLM integration and image-based diagnosis.