RCT Tagger is an automated tool designed to identify randomized controlled trial (RCT) articles. It uses machine learning algorithms to estimate the probability that a given article reports the results of an RCT based on its title, abstract and other metadata. The tool was developed to help streamline the process of conducting systematic reviews, which often require screening thousands of article to find relevant RCTs. By automating this step, RCT Tagger can significantly reduce the manual labor involved and improve efficiency.