What is Redis? Redis is an open source (BSD licensed), in-memory data structure store, used as a database, cache and message broker. Why should we use Redis? By default, Rails uses the database to cache internal application data which can be expensive to generate (menu trees, views, filter results, etc), and to keep cached page contents. Since the database also handles many queries for normal page requests, it can create a bottleneck and increase load-times. Redis provides an alternative caching backend for Rails, taking that work off the database, which is vital for scaling to a larger number of logged-in