The Official NASA Task Load Index (TLX) App, widely regarded as the gold standard for measuring subjective workload across a wide range of industries, enables researchers to easily perform assessments on operators working with various human-machine interface systems. By incorporating a multi-dimensional rating procedure, the NASA TLX derives an overall workload score based on a weighted average of ratings on six sub scales: ∙ Mental Demand ∙ Physical Demand ∙ Temporal Demand ∙ Performance ∙ Effort ∙ Frustration Originally developed as a paper and pencil questionnaire by NASA Ames Research Center’s (ARC) Sandra Hart in the 1980s, the NASA TLX is the benchmark against which the efficacy of other measures, theories, or models are judged. The NASA TLX has been successfully used around the world to assess workload in various environments such as aircraft cockpits; command, control, and communication (C3) workstations; supervisory and process control; and simulations and laboratory tests. The NASA TLX app for iOS dramatically increases the outreach and accessibility for the research and development community, and enables mobile and contextual assessments (e.g., in an airplane cockpit during/after flight, rather than at a desktop computer in a lab). It offers several key features that benefits both researchers and participants: Privacy The NASA TLX has been designed to ensure the privacy of research participant data. The NASA TLX anonymizes all results and does not send any personal identifiable information (PII) to any data servers. Location Flexibility The NASA TLX app can be used anywhere, even without a network connection, so researchers can have participants complete a NASA TLX evaluation in the field, outside the confines of a desktop office environment. The NASA TLX results are calculated on the device, and, once a network connection is available, collected data can be securely uploaded to servers for analysis. This frees researchers from being burdened by the task of tracking individual paper forms. Simple Study Setup Researchers can set up studies quickly and reduce typing on the NASA TLX app by scanning a pre-generated QR code from within the app, which automatically populates the study name, subject ID, and trial number in the app.