Textbook of Linux

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Redis

An in-memory data structure store.

Redis stores key-value pairs in memory and supports a rich set of value types beyond simple strings: hashes, lists, sets, sorted sets, streams, bitmaps, hyperloglog probabilistic counters, and (via modules) JSON, time series, full-text search, and graph queries. The commands operate atomically on those structures, which makes Redis well suited to caching, session stores, leaderboards, rate limiting, and message queues.

Salvatore Sanfilippo (antirez) started Redis in 2009. The licence change in 2024 from BSD to a dual SSPL/RSALv2 arrangement was widely seen as a breaking move and prompted several community forks: Valkey (under the Linux Foundation, with substantial cloud-provider backing) and KeyDB are the most prominent. Distribution packagers have largely shifted to Valkey for new packages.

Redis remains widely deployed in production despite the licensing controversy. The combination of a simple data model, predictable performance, and a clean wire protocol made it nearly ubiquitous in the 2010s, and many existing workloads continue to run on Redis instances even as new deployments increasingly choose Valkey for license-clarity reasons.

Debian/Ubuntu: sudo apt install redis-server
Fedora/RHEL:   sudo dnf install redis
Arch:          sudo pacman -S redis
macOS:         brew install redis