"What is ONNX?
ONNX is a open format to represent deep learning models. With ONNX, AI developers can more easily move models between state-of-the-art tools and choose the combination that is best for them. ONNX is developed and supported by a community of partners."
...is a specification standard for neural network models, so that different deep learning libraries can work together."
"ONNX was created by Microsoft and Facebook. The ONNX specification appears to have official support from Amazon (AWS), as well as hardware companies AMD, ARM, IBM, Intel, Huawei, NVIDIA, and Qualcomm.
Neural network tools initially supported by ONNX v1 include CNTK, PyTorch, Apache MXNet, Caffe2, and TensorRT. Noticeably missing is official support from Google and their TensorFlow library. However, it appears that there is some sort of converter that allows indirect interoperability with TensorFlow."