I'd say the first step for you (or any new developer that comes to the project) is to document the data model. What are the tables in the DB? What data goes whe

I'd say the first step for you (or any new developer that comes to the project) is to document the data model. What are the tables in the DB? What data goes where? What tables change on a day to day basis, and which are "stable". Where are user accounts? Once that is done, you should document how the system interacts with other systems. Logins? Single sign on? External APIs that the system calls? External clients that call the app? With these things done (which might take some time to figure out), you should think about writing a HOWTO for new developers. You really don't want to be the only person working on this, it will be a lot of stress otherwise. Imagine a new developer joins tomorrow. What should they look at first? This is a nice tool for showing "code tours" of a new code base you could use: https://github.com/partyparrot/codetours https://github.com/partyparrot/codetours