Language learning applications (LL Apps), especially those that can be downloaded to a mobile device, are popular, widely available and represent a potentially useful tool for language teachers and their students. However, concerns exist that many LL Apps are inadequately aligned with second language acquisition (SLA) theory, and/or poorly suited to the expectations and classroom requirements of language teachers. The current study examines these concerns by providing six language teachers with opportunities to use two popular LL Apps over the period of six weeks. During and after this period, qualitative data were gathered from the teachers by way of questionnaires and interviews. Teachers' elaborations of the perceived affordances of the LL Apps for their language teaching were then coded against the methodological principles of a Task-based Language Teaching (TBLT) framework (Doughty & Long, 2003). Analysis indicated that although some methodological principles central to TBLT were evident in the affordances offered by the LL Apps, many were not, or only minimally so. Concrete suggestions about how to more strongly align LL App design with the principles of TBLT are provided, and the important role of the teacher in the LL Apps design process is emphasized.