Twitter is the leading micro-blogging and social network service and is attracting an enormous amount of attention in recent years. Users on Twitter generate an abundance of information every day, establishing Twitter as the focal point for analyzing and visualizing social media data. In this paper, we present a web tool for visualizing Twitter data, TweetViz. TweetViz offers several different kinds of visualizations that can pertain to a Twitter user or any keyword or hashtag entered through the interface. TweetViz also includes a so called Streamgraph visualization that represents topic distribution in a set of tweets. The topic distributions are created using LDA (Latent Dirichlet Allocation).