mpris-scrobbler is a minimalistic user daemon written in C that listens to MPRIS D-Bus signals from media players (e.g., Spotify, Rhythmbox) and submits currently playing tracks to Last.fm, Libre.fm, and ListenBrainz scrobbling services. It consists of a daemon binary and a signon helper for authentication. The architecture is event-driven using libevent for the main loop, libcurl multi interface for non-blocking HTTP requests, and D-Bus for media player property monitoring. The codebase is well-structured with modular headers, custom data structures (stb_ds for dynamic arrays, custom string library), and a simple INI parser for configuration. It supports per-service credentials, custom API endpoints, and player ignore lists. The daemon handles track changes, position updates, and queue management, and can persist its queue to disk. Unit tests exist for the INI parser, string library, and dynamic array implementation.