Other deep learning libraries
Besides the big two, TensorFlow and Keras, there are other competitors that are making their way in the world of deep learning. We already discussed PyTorch, but there are more. Here we talk about them briefly.
Caffe
Caffe is also a popular framework developed at UC Berkeley (Jia, Y., et.al. 2014). It became very popular in 2015-2016. A few employers still demand this skillset and scholarly articles still mention its usage. However, its usage is in decay in part due to the major success of TF and the accessibility of Keras.
Note also the existence of Caffe2, which is developed by Facebook and is open source. It was built based on Caffe, but now Facebook has its new champion, PyTorch.
Theano
Theano was developed by Yoshua Bengio's group at the University of Montreal in 2007 (Al-Rfou, R., et.al. 2016). Theano has a relatively old user base that probably saw the rise of TF. The latest major release was made in late 2017 and, although there are no clear plans of new major releases, updates are still being made by the community.
http://deeplearning.net/software/theano/
Honorable mentions
There are other alternatives out there that may not be as popular, for a variety of reasons, but are worth mentioning here in case their future changes. These are as follows:
