C++ library for various versions of CIM and CGMES:
https://github.com/cim-iec/libcimpp
Online class documentation of CIM:
https://cim.fein-aachen.org/libcimpp/doc/IEC61970_16v29a/annotated.html
Supports import for DL, DY, EQ, GL, SV, SSH, TP CGMES profiles and all IEC61970 CIM classes
Export is only partially available
Python library for CGMES (v2.4.15):
https://github.com/sogno-platform/cimpy
Supports import and export for DL, DY, EQ, GL, SV, SSH, TP CGMES profiles
Java library for CGMES (v2.4.15 and v3.0 coming soon):
https://github.com/powsybl/powsybl-core
Java library used to import a set of EQ, TP, SSH and SV profiles and export the updated SSH and SV profiles. It could be used to import EQ profile only (ongoing work). Support of DL and GL profiles. Full export EQ in progress.
Online documentation:
https://www.powsybl.org/pages/documentation/grid/formats/cim-cgmes.html
Bidding python:
https://www.powsybl.org/pages/documentation/developer/scripting/python