  Bus factor (BF) is a metric that tracks knowledge distribution in a project.
It is the minimal number of engineers that have to leave for a project to
stall. Despite the fact that there are several algorithms for calculating the
bus factor, only a few tools allow easy calculation of bus factor and
convenient analysis of results for projects hosted on Git-based providers.
  We introduce Bus Factor Explorer, a web application that provides an
interface and an API to compute, export, and explore the Bus Factor metric via
treemap visualization, simulation mode, and chart editor. It supports
repositories hosted on GitHub and enables functionality to search repositories
in the interface and process many repositories at the same time. Our tool
allows users to identify the files and subsystems at risk of stalling in the
event of developer turnover by analyzing the VCS history. The application and
its source code are publicly available on GitHub at
https://github.com/JetBrains-Research/bus-factor-explorer. The demonstration
video can be found on YouTube: https://youtu.be/uIoV79N14z8
