This paper presents Vizzly, a middleware for the interactive browsing of large sensor network data sets. Provided map and line plot widgets allow to visualize structured data from mobile and static sensors. A user is completely free in selecting sensor data based on time and location, suitable levels of temporal and spatial detail are automatically chosen by the Vizzly server. Vizzly automatically adapts to user interactions, new data is automatically loaded when query parameters change. Request response times are significantly reduced by the use of caching techniques, most requests are served from already pre-computed data that is stored in the memory of the Vizzly server. Vizzly has already been successfully integrated into the PermaSense and OpenSense projects, a single instance is currently handling more than 550 millions of data points.