PyTorch is an open source deep learning platform created by Facebook's AI research group. Like NumPy, PyTorch is a library for tensor operations but adds support for GPU and other hardware acceleration and efficient tools for AI researchers to explore different domains. While it started out as a Python-based successor to the Lua Torch framework, PyTorch has expanded in scope to be not just a research platform but also a deployment platform. Organizations such as Stanford and Salesforce rely on PyTorch to fuel their machine learning research and offerings. And PyTorch relies on CircleCI to create a smooth and reliable PR process for their many open source contributors, and to ship code more quickly and with less overhead than their previous solution.