The NASA Task Load Index (NASA-TLX) is a well-established rating system for assessing mental workload. Though first intended for aerospace system design and evaluation at the NASA Ames Research Center, it is currently used to assess the workload many types of products and systems impose. These systems include anything from instructional technology and consumer products to surgical tools and process control systems. The Vis TLX app provides a simple way to administer the NASA-TLX and to export the collected data. The User Experience Lab at the University of Kentucky’s Vis Center uses this version of the NASA-TLX as their standard subjective workload assessment tool.