What tools have you built?

This is sort of a follow up to this post:

Invest in building custom tools

Ben Halpern Jun 16 1 min read

#productivity

I am curious to what tools people have built that you use either locally or in production that helps you be more efficient. From automating, to building, code generation, scheduling/reminders, or anything else.

Even if you never released it (you should!) I would be interested in knowing what non well-known tools people have made to make their own developer lives easier