Salvatore Sanfilippo's in-memory key/value store and the Linux Foundation fork Valkey (2024) after Redis's BSL move. Both widely deployed.
Valkey is an open-source in-memory key–value database, used as a distributed cache and message broker, with optional durability. Because it holds all data in memory and because of its design, Valkey offers low-latency reads and writes, making it particularly suitable for use cases that require a cache. Valkey is a fork of Redis, the most popular NoSQL database and one of the most popular databases overall. Valkey and Redis have been used by companies including Twitter, Airbnb, Tinder, Yahoo, Adobe, Hulu, Amazon and OpenAI, and Valkey is supported by Alibaba Cloud, AWS, Ericsson, Google Cloud, Heroku, Oracle, Percona, and Verizon.