ions on Top of Deep Learning Libraries As part of efforts to make deep learning research and applications more accessible, several libraries have been introduced that provide abstractions for high-level tasks in building neural networks. While hiding complex internals by abstraction can come at the price of flexibility and optimization, the rapid prototyping qualities of these tools are often appreciated by the community. Fast.ai Fast.ai is an opinionated wrapper for PyTorch that aims to simplify the use of neural networks by providing the user with best-practices presets and workflows out of the box. While its speed of evolution has led to outdated or missing documentation, the structure does deliver on computer vision tasks, among others. For example, using generative models, Fast.ai provides state-of-the-art deep learning tools to colorize blackand-white pictures and movies and generate super-resolution images. Keras Keras is a high-level Python deep learning API specification for building and training neural networks. The API is very well designed and allows for a user-friendly, modular, composable, and easily extensible interface. Several frameworks