SpacetimeDB is a real-time database system that enables developers to upload application logic directly into the database as modules, eliminating the need for traditional backend servers. Clients connect directly to the database using language-specific SDKs (Rust, C#, TypeScript, C++, Unreal) and receive real-time updates when data changes. The system features a Rust-based core server, WebSocket-based synchronization, ACID transactions, and a code generation system that creates language bindings from module definitions. Notable features include schema evolution capabilities, scheduled procedures, and row-level security. The entire backend of MMORPG BitCraft Online runs as a single SpacetimeDB module, demonstrating its capacity for complex, high-performance applications.