How to open a .onnx file (Windows, Mac, Linux)

Q: Why can't I open my .onnx file?

Usually your computer lacks an app that understands ONNX. Install one of the apps listed here, or convert the file to a more common format.

A .onnx file is a Open Neural Network Exchange. If double-clicking does nothing, your computer simply does not have an app that reads ONNX yet. Here is how to fix that on each operating system, using free software wherever possible.

Open a .onnx file step by step

Confirm the file really is a .onnx. Drop it into the WhatFileType file identifier, which reads its signature without uploading anything.
On Windows, open it with Netron (graph viewer) or Python (onnx, onnxruntime).
On Mac, use Netron (graph viewer) or Python (onnx, onnxruntime).
On Linux, try Netron or Python (onnx, onnxruntime).
Still stuck? Convert the .onnx to Various framework formats, which opens more widely.

Best apps to open .onnx files

Windows

Netron (graph viewer)
Python (onnx, onnxruntime)

macOS

Netron (graph viewer)
Python (onnx, onnxruntime)

Linux

Netron
Python (onnx, onnxruntime)

Web

Netron web app
ONNX Runtime Web

Before you open it: Generally safe. An ONNX file is a model graph plus weights, run by a dedicated runtime. As always, only run models from sources you trust.

Frequently asked questions

Why can't I open my .onnx file?

Almost always because no installed app understands ONNX. Install one of the apps above, or convert the file to a format your existing software already reads.

How do I open an ONNX file?

To see its structure, open it in Netron, a free model viewer. To run it, use ONNX Runtime in Python, C++, JavaScript or C#.

What is ONNX used for?

Moving trained models between frameworks and runtimes. You can train in PyTorch, export to ONNX, and deploy with an optimised runtime on many platforms.