Anki is a mature, cross-platform spaced-repetition flashcard application. While it is fundamentally an end-user product, it contains significant embedded algorithmic and data-analysis components (FSRS memory-state scheduling, revlog analytics, retention simulation) that make it a hybrid of application and computational research. The production system consists of a Rust backend that owns all core logic, scheduling, SQLite persistence, sync, and media management; a Python Qt desktop frontend (`aqt`); a TypeScript/Svelte web UI for modern editors, graphs, deck options, and image occlusion; and a standalone sync server binary. Communication between languages is driven by protobuf service definitions, with generated bindings for Rust, Python, and TypeScript.