Seastar is a high performance C++ application framework for high concurrency server applications.

A good place to start is the Tutorial or Multi-page version.

Please see:

Futures and Promises Documentation on futures and promises, which are the seastar building blocks.
Future Utilities Utililty functions for working with futures
Memory management Memory management
Networking TCP/IP networking
File Input/Output File Input/Output
Multicore Multicore support
Fibers Utilities for managing loosely coupled chains of continuations, also known as fibers
Seastar threads Support for traditional threaded execution
rpc - remote procedure call framework Build high-level communication protocols
WebSocket (experimental) Implement a WebSocket-based server
FileSystem Notifier (experimental) Implement a filesystem modification notifier.

View the Seastar compatibility statement for information about library evolution.