  Open Source Software (OSS) is a major component of our digital
infrastructure, yet more than 80% of such projects fail. Seeking less
uncertainty, many OSS projects join established software communities, e.g., the
Apache Software Foundation (ASF), with established rules and community support
to guide projects toward sustainability. In their nascent stage, ASF projects
are incubated in the ASF incubator (ASFI), which provides systematic mentorship
toward long-term sustainability. Projects in ASFI eventually conclude their
incubation by either graduating, if successful, or retiring, if not.
  Time-stamped traces of developer activities are publicly available from ASF,
and can be used for monitoring project trajectories toward sustainability. Here
we present a web app dashboard tool, APEX, that allows internal and external
stakeholders to monitor and explore ASFI project sustainability trajectories,
including social and technical networks.
