The open-source models and libraries that power ImageUpscalerFree, and their licences.
2026/09/11
Upscaling on ImageUpscalerFree runs entirely inside your browser. It is built on open-source work, credited here as those licences require.
Both models are by Philip Hofmann (Phhofm/models) and are licensed under CC BY 4.0.
| Model | Used for | Source |
|---|---|---|
2xNomosUni_span_multijpg | 2× upscaling | Release page |
4xNomosUni_span_multijpg | 4× upscaling | Release page |
Modifications: the published ONNX files were altered in two ways. The output tensor's symbolic dimension names were renamed so they no longer collide with the input's, which otherwise prevents ONNX Runtime from allocating the larger output buffer. No weights were changed.
Both models use the SPAN architecture, from Swift Parameter-free Attention Network for Efficient Super-Resolution (Apache 2.0).
ONNX Runtime Web by Microsoft, licensed under the MIT licence, executes the models in your browser using WebGPU where available and WebAssembly otherwise.
Your image is never uploaded. The model files are downloaded to your device the first time you upscale something, and everything after that happens locally — which is also why the first run takes longer than later ones.