Theano vs Chainer: What are the differences?

What is Theano? Define, optimize, and evaluate mathematical expressions involving multi-dimensional arrays efficiently. Theano is a Python library that lets you to define, optimize, and evaluate mathematical expressions, especially ones with multi-dimensional arrays (numpy.ndarray). Using Theano it is possible to attain speeds rivaling hand-crafted C impleme.

What is Chainer? A Powerful, Flexible, and Intuitive Framework for Neural Networks. It is an open source deep learning framework written purely in Python on top of Numpy and CuPy Python libraries aiming at flexibility. It supports CUDA computation. It only requires a few lines of code to leverage a GPU. It also runs on multiple GPUs with little effort.

Theano and Chainer can be primarily classified as "Machine Learning" tools.

Theano and Chainer are both open source tools. Theano with 8.88K GitHub stars and 2.5K forks on GitHub appears to be more popular than Chainer with 4.98K GitHub stars and 1.32K GitHub forks.