Marcalyc is an online tool for tagging journal articles in XML-JATS format. It was created by Redalyc to make the tagging process accessible without advanced technical knowledge. Tagging articles in XML-JATS provides benefits like improved discoverability, preservation of content, and interoperability across systems. Marcalyc guides users through tagging the front matter, body, and back matter of articles according to JATS specifications to produce outputs in multiple formats.