Microsoft Cognitive Toolkit—or more simply CNTK—is the deep learning toolkit that underlies the AI capabilities of Microsoft’s services including Skype, Cortana, Bing, and Xbox. It handles multidimensional dense or sparse data from Python, C++, or BrainScript, and includes a wide variety of neural network types: FeedForward (FFN), Convolutional (CNN), Recurrent/Long Short Term Memory (RNN/LSTM), batch normalization, and sequence-to-sequence with attention, for starters.
The Cognitive Toolkit supports reinforcement learning, generative adversarial networks, supervised and unsupervised learning, automatic hyperparameter tuning, and the ability to add new, user-defined, core components on the GPU from Python. It is able to do parallelism with accuracy on multiple GPUs and machines, and it can fit even the largest models into GPU memory.
— Martin Heller