Systematic searching aims to find all possibly relevant research records from multiple sources to collate an unbiased and comprehensive set of bibliographic records. Along with bibliographic databases, systematic reviewers use a variety of additional methods to minimise procedural bias, including assessing records that are cited by and that cite a set of articles of known relevance (citation chasing). Citation chasing exploits connections between research articles to identify relevant records for consideration in a review by making use of explicit mentions of one article within another. Citation chasing is a popular supplementary search method because it helps to build on the work of primary research and review authors. It does so by identifying potentially relevant studies that might otherwise not be retrieved by other search methods; for example, because they did not use the review authors’ search terms in the specified combinations in their titles, abstracts or keywords. Here, we describe an open source tool that allows for rapid forward and backward citation chasing. We introduce citationchaser, an R package and Shiny app for conducting forward and backward citation chasing from a starting set of articles. We describe the sources of data, the backend code functionality, and the user interface provided in the Shiny app.