Redis

In-memory data structure store that serves as a database, cache, message broker, and streaming engine. Supports 18+ data structures including strings, hashes, lists, sets, sorted sets, streams, JSON, and vector types, delivering sub-millisecond latency for real-time applications.

Redis is widely adopted across enterprises and startups. It differentiates from simple key-value caches like Memcached with persistence, pub/sub, Lua scripting, and native support for complex types and search. Client libraries exist for all major languages and integrate with popular frameworks and cloud platforms.

Key capabilities:

• 18+ data structures: strings, hashes, lists, sets, sorted sets, streams, JSON, vectors
• Pub/sub messaging and Redis Streams for real-time data pipelines
• Persistence options: RDB snapshots and AOF for durability
• Clustering and replication with automatic failover
• Cloud, on-prem, or hybrid deployment options
• Redis Search for secondary indexes and full-text search

Use cases: Session caching and API response caching, rate limiting and authentication token storage, leaderboards and real-time rankings, message queues and job queues, real-time analytics and event sourcing. Developers use it as a fast backing store for LangChain and other AI tooling, as a vector store for RAG, and for caching database queries with TTL-based invalidation.