Redis is a data structure server. It is open-source, networked, in-memory, and stores keys with optional durability. The development of Redis has been sponsored by Redis Labs since June 2015. Before that, it was sponsored by Pivotal Software and by VMware. According to the monthly ranking by DB-Engines.com, Redis is the most popular key-value database. Redis has also been ranked the #1 NoSQL (and #4 database) in User Satisfaction and Market Presence based on user reviews, the most popular NoSQL database in containers, and the #1 NoSQL among Top 50 Developer Tools & Services. The name Redis means REmote DIctionary Server.