NoSQL solutions have one thing in common. They are generally designed for horizontal scalability. So its no wonder that lot of applications in the â€œtwitterâ€ world have picked NoSQL based datastores for their persistence layer. Here is a collection of these apps from MyNoSQL blog. Twitter uses Cassandra MusicTweets used Redis [ Ref ] â€“ The site is dead, but you can still read about it Tstore uses CouchDB Retwis uses CouchDB Retwis-RB uses Redis and Sinatra ?? - No idea what sinatra is. Will have to look into it. [ Update: Sinatra is not a DB store ] Floxee uses MongoDB Twidoop uses Hadoop Swordfish built on top of Tokyo Cabinet comes with a twitter clone app with it. Tweetarium uses Tokyo Cabinet References NoSQL Twitter Applications More NoSQL Twitter apps Do you know of any more ?