I organize notes and action items in a paper notebook in front of me or a text file in another editor pane. I read the code. I search and diff with standard POSIX utilities that are available in every environment. In the languages which support it, I try ideas and answer my own questions in a REPL.

Practice leaning on tooling all day and living without it will feel unthinkable. Practice doing without, and you'll find you need very little.