Is there any software missing from this list? Open an issue!
QDYN (Fortran) – comprehensive package for quantum dynamics and control. The implementation of the krotov package was inspired by QDYN.
QuTiP (Python) – Quantum Toolbox in Python . Provides the basic data structures for the krotov. Contains implementation of GRAPE and CRAB.
WavePacket (Matlab)  – Implemenentation of monotonically converging iterative schemes for wavepacket dynamics
DYNAMO (Matlab)  – Implementation of GRadient Ascent Pulse Engineering (GRAPE), including concurrent/sequenetial/hybrid schemes
QEngine (C++)  – Implementation of “GRadient Optimization Using Parametrization” (GROUP) 
The following packages integrate closely with krotov.
weylchamber (Python) – Package for analyzing two-qubit gates in the Weyl chamber. Provides Local-Invariants and Perfect Entangler functionals for use with krotov.