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microsoft/onnxruntime

Analysis updated 2026-06-21

20,424C++Audience · developerComplexity · 4/5LicenseSetup · moderate

TLDR

Microsoft's open-source engine that runs trained machine learning models faster across different hardware and programming languages, using a standard model format called ONNX.

Mindmap

mindmap
  root((repo))
    Inference
      PyTorch models
      TensorFlow models
      scikit-learn models
    Training
      Multi-GPU support
      Transformer speedup
    Languages
      Python
      JavaScript
      C# Java
    Hardware
      NVIDIA GPU
      CPU fallback
      Mobile edge
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filefunction / class

What do people build with it?

USE CASE 1

Run a PyTorch or TensorFlow model in production at lower cost and latency by converting it to ONNX and using ONNX Runtime for inference.

USE CASE 2

Deploy ML inference inside a web browser or Node.js app using the JavaScript API.

USE CASE 3

Speed up training of transformer models on multi-GPU NVIDIA setups by adding one line to a PyTorch training script.

USE CASE 4

Run ML inference on mobile or edge devices without depending on a specific framework.

What is it built with?

C++PythonC#JavaJavaScriptCUDAONNX

How does it compare?

microsoft/onnxruntimecatchorg/catch2maaassistantarknights/maaassistantarknights
Stars20,42420,38120,659
LanguageC++C++C++
Setup difficultymoderatemoderatemoderate
Complexity4/52/53/5
Audiencedeveloperdevelopergeneral

Figures from each repo's GitHub metadata at analysis time.

How do you get it running?

Difficulty · moderate Time to first run · 30min

GPU acceleration requires a CUDA-compatible NVIDIA GPU and matching CUDA drivers.

Use freely for any purpose including commercial products, MIT license requires keeping the copyright notice.

In plain English

ONNX Runtime is Microsoft's open-source, cross-platform machine learning inference and training accelerator written in C++. ONNX (Open Neural Network Exchange) is a standard format for representing machine learning models, and ONNX Runtime is the engine that runs those models efficiently across different hardware and operating systems. For inference, running a trained model to make predictions, ONNX Runtime supports models from deep learning frameworks like PyTorch and TensorFlow/Keras, as well as classical machine learning libraries like scikit-learn, LightGBM, and XGBoost. It delivers faster performance by leveraging hardware accelerators where available and applying graph optimizations and transforms to the model. It is compatible with different hardware, drivers, and operating systems. For training, ONNX Runtime can accelerate model training time on multi-node NVIDIA GPU setups for transformer models, requiring only a one-line addition to existing PyTorch training scripts. The library is used to reduce inference costs and latency in production machine learning deployments. APIs are available for Python, C#, C++, Java, JavaScript (including web browsers and Node.js), and other languages. The project is MIT-licensed.

Copy-paste prompts

Prompt 1
How do I convert a PyTorch model to ONNX format and then run inference on it using onnxruntime in Python? Show a complete example with a simple image classifier.
Prompt 2
Using onnxruntime-web, show me how to load an ONNX model in a browser and run inference on user-provided input without a server.
Prompt 3
How do I enable GPU acceleration in onnxruntime Python for an NVIDIA GPU using the CUDAExecutionProvider?
Prompt 4
Show me how to add onnxruntime training acceleration to an existing PyTorch training loop with minimal code changes.
Prompt 5
How do I use onnxruntime in a C# .NET application to run inference on a pre-trained model?

Frequently asked questions

What is onnxruntime?

Microsoft's open-source engine that runs trained machine learning models faster across different hardware and programming languages, using a standard model format called ONNX.

What language is onnxruntime written in?

Mainly C++. The stack also includes C++, Python, C#.

What license does onnxruntime use?

Use freely for any purpose including commercial products, MIT license requires keeping the copyright notice.

How hard is onnxruntime to set up?

Setup difficulty is rated moderate, with roughly 30min to a first successful run.

Who is onnxruntime for?

Mainly developer.

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