The research study explored online language learners' self-directed language learning (SDLL) experiences, benefits, motivations, and challenges when employing educational tools like Duolingo in an out of classroom context. To gain insights into SDLL, in-depth and semi-structured interviews with 10 Duolingo users were conducted. Study results indicated that learners manage various human and material learning resources in complementary ways to accomplish their language learning goals. Importantly, Duolingo learners self-monitor their learning process through feelings of knowing, content evaluation, and judgments of the adequacy of information and resources available. In addition, the study found that Duolingo learners highly rely on the features of learning technology to track, monitor, and reinforce their learning. Additionally, learners in this study were mostly driven by intrinsic needs and interests, such as culture, travel, and brain training, rather than obtaining certificates, scores, or grades. While most existing studies on self-directed language learning (SDLL) with technology have been conducted in a formal learning context, the results of this study provide some insights into SDLL independent of formal school contexts.