JDA (Java Discord API) is a comprehensive Java library for building Discord bots. It provides a full-featured client for Discord's REST API and Gateway (WebSocket) protocol, including support for slash commands, message components (buttons, select menus, modals), voice/audio (Opus, DAVE encryption), auto-moderation, scheduled events, forum channels, polls, stickers, soundboard, and sharding. The architecture is event-driven with a rich hierarchy of typed events, an asynchronous request system (RestAction) with combinators (map, flatMap, delay), and a fluent manager pattern for entity modifications. It includes a custom component tree with immutable replacement, ETF (Erlang External Term Format) encoding for gateway payloads, and a thread-safe caching layer using Trove maps. The codebase is well-structured with extensive unit tests, snapshot testing, and architecture compliance tests. It is actively maintained with regular releases and a large community.