This new Cedefop CrowdLearn study undertakes a comparative analysis of skill development and workplace learning practices among two major types of online platform work: online freelancing and microwork. It combines information on microworkers drawn from Amazon’s Mechanical Turk platform with the original CrowdLearn sample of online freelancers surveyed from three major online labour platforms (Fiverr, Upwork, PeoplePerHour). The research compares the types and frequency of use of workplace learning activities and self-regulated learning strategies adopted by these two main types of crowdworker. The first of its kind internationally, this comparative study generates additional insights and policy recommendations on how to foster workplace learning and skill development in the platform economy. It highlights the potential role of microwork as a viable avenue for labour market integration, income supplementation and skill development opportunities for workers who otherwise underutilise their skills. Supporting skill development in 'voluntary' microwork could be a relevant course of policy action for the EU in dealing with the economic fallout and recovery from the COVID-19 pandemic.