This answer assumes that the question does not refer to Orbital Replacement Units.
The definitive reference needed to answer this question for the US side of the ISS is the International Space Station In-Flight Maintenance Book aka the IFM Checklist. Unfortunately the only one I can find online is quite old, December 2000. Johnson Space Center reorganizations have even changed the organization which owns this document. It is now the Operations Support Officer group, not the Maintenance Repair Group.
The Reference section of this document contains tool and hardware lists, too lengthy to reproduce here (especially for an outdated document). Here's the relevant part of the table of contents, and some representative pages.

tool kit list

Spare/diagnostic cabling

The bulk of the document contains procedures for performing maintenance and repair.
A more up-to-date tool list can be found in the links used in the answer to this question.
A link to an updated version of the IFM Checklist would be most welcome.