ccNexus is a desktop application (built with Wails v2, Go backend + web frontend) and a headless server that acts as a smart proxy for multiple AI API endpoints, including Claude, OpenAI Chat, OpenAI Responses, and Gemini. It manages endpoint rotation with automatic failover, credential token pools (API keys, access tokens, refresh tokens), and real-time format conversion between the different API protocols. The system provides a full-featured GUI for managing endpoints, viewing usage statistics, configuring backup/restore (WebDAV, local, S3), launching Claude Code or Codex CLI terminals, and applying visual themes. A separate web UI is available for headless deployments via Docker. The architecture follows a layered design: a proxy layer handles request routing, authentication, and streaming response transformation; a transformer layer converts between API formats using a registry of converters; a storage layer persists endpoints, credentials, and stats in SQLite; and a service layer orchestrates higher-level operations like backup, updates, and terminal launching. The codebase demonstrates strong engineering practices including thread-safe configuration, adapter patterns for storage abstraction, SSE for real-time stats, and comprehensive contract tests. Notable features include zero-cost endpoint testing, incremental stats updates, and a credential lifecycle management system with rate limit tracking and automatic cooldown. While primarily an application, ccNexus includes some data-oriented components such as token counting, usage statistics aggregation, and credential rate limit parsing. However, these serve the operational needs of the proxy rather than constituting a data research pipeline. The project is actively maintained with a responsive issue tracker and regular releases.