Deep learning frameworks

There are a plenty of deep learning toolkits and libraries for different kinds of platforms. For a long time, the three most popular of them were Theano (Python), Torch (Lua), and Caffe (C++). Somehow, Caffe became an industrial standard, while Theano and Torch were mostly used among researchers. I call these three libraries the first generation of deep learning frameworks. Most of the pre-trained neural networks that are available on the internet are still in Caffe format. They had their own problems, so the next generation of frameworks followed in several years. If the first generation was created mainly by efforts of individual researchers, the second generation was pushed by big IT companies. Today, apart from Apple, every internet giant has its own open source deep learning framework: Google has TensorFlow and Keras, Microsoft has CNTK, Facebook...