TensorFlow

Open-source ML framework using dataflow graph computation, supporting CPUs, GPUs, and TPUs. 189K+ GitHub stars. Dominated deep learning research and production for years before PyTorch's rise.

TensorFlow and its ecosystem (TensorFlow Lite, TF Serving, TensorBoard, Keras) underpinned massive amounts of ML research and production systems worldwide. OSDI 2016. By Abadi, Barham, Chen, Dean et al. Apache 2.0.