Redis

Redis is an open-source in-memory data structure store created by Salvatore Sanfilippo, known as antirez, in 2009 and now developed by Redis Inc., serving as a database, cache, message broker, and streaming engine used by millions of developers and over ten thousand organizations including Twitter, GitHub, Stack Overflow, and Snapchat for high-performance real-time applications requiring sub-millisecond latency. The data structure support goes far beyond simple key-value storage, providing strings, lists, sets, sorted sets with scores, hashes for object storage, bitmaps for efficient bit-level operations, hyperloglog for cardinality estimation, geospatial indexes for location queries, and streams for log-based messaging with consumer groups, enabling developers to model diverse data patterns without multiple specialized systems. The in-memory architecture stores all data in RAM for exceptional performance, achieving over one hundred thousand operations per second on a single core and millions per second with pipelining, with optional persistence through point-in-time snapshots and append-only files for durability, and replica and cluster modes for horizontal scaling. The pub and sub messaging provides real-time message broadcasting, while streams enable persistent log processing with consumer groups for reliable message delivery. The Lua scripting engine executes atomic server-side operations, the functions feature provides server-side programmability, and the module system extends capabilities with RediSearch for full-text search, RedisJSON for document storage, RedisGraph for graph queries, RedisTimeSeries for time series, and RedisBloom for probabilistic data structures. The Redis Cluster provides automatic sharding and failover across multiple nodes. The version seven added functions, ACLs, and multi-part AOF. Designed for backend developers, data engineers, and architects building real-time systems.