Availability : Open Source(BSD Licensed)

Redis means REmote DIctionary Server.

It is open source and in-memory data structure store, used as a database, cache and message broker

It supports many programming languages.

It supports data structures including strings, hashes, lists, sets, sorted sets with range queries, bitmaps, hyperlogs, geospatial indexes with radius queries and streams.

It has built-in replication, Lua Scripting, LRU eviction, transactions and different levels of on-disk persistence.

It provides high availability via Redis Sentinal and automatic partitioning with Redis Cluster

Transactions

Pub/Sub

Lua Scripting

Keys with a limited time to live

LRU eviction of keys.

Automatic failover