Valkey is a high-performance in-memory data structure server, forked from Redis under a BSD-3-Clause license. It serves as a key-value store with support for strings, hashes, lists, sets, sorted sets, streams, geospatial indexes, and more. The architecture is event-loop-driven (single-threaded main loop with background I/O threads for persistence, replication, and lazy freeing). It supports clustering (up to 16384 slots), replication (leader-follower with partial resync), persistence (RDB snapshots, AOF logs), Lua scripting (EVAL/FUNCTION), a pluggable module API, TLS, RDMA, and advanced features like client-side caching, hot-key detection, and replication throttling. Key entry points include the `valkey-server` daemon, `valkey-cli` client, `valkey-benchmark` load generator, and `valkey-check-rdb`/`valkey-check-aof` integrity tools. External dependencies include jemalloc (default allocator), Lua 5.1, LZ4, Zstd (optional), OpenSSL (TLS), and RDMA libraries (optional). The codebase is actively maintained with extensive unit and integration tests, and demonstrates high craftsmanship in its lock-free queues, streaming compression, and data structure implementations.