ImpLib SDK
ImpLib SDK produces custom Import libraries for Windows DLL
... the SDK is available for free, redistributing these files is not allowed according to the current license agreements. An alternative is to generate these import libraries using the ImpLib SDK, as it doesn't restrict redistribution.
One of the ImpLib SDK tools is DLL2DEF. It's a command-line utility to extract the dynamic-link library symbols in plain text format.
Guide: https://implib.sourceforge.io/EN.HTM
Author page: https://www.celersms.com/org/vkamenar.htm