Thesys released OUI-1 on September 8, 2026, a fine-tuned DiffusionGemma model for generating interfaces in OpenUI Lang. The model writes a structured UI description that an application can check before trying to render it.
The OpenUI Lang parser catches structural errors such as an invented component, an unsupported property or a section left disconnected from the screen.
Thesys says OUI-1 scored 71.7% on its Generative UI Benchmark. The base DiffusionGemma model scored 13.0% under the same test. The company reports that training with parser feedback and repaired examples reduced both types of error. The benchmark measures the developer's specified UI tasks.
OUI-1 has 26 billion total parameters, with about four billion active for a given token. Thesys says the FP8 model can run on an RTX 5090. Its weights are available on Hugging Face under Apache 2.0.
A separate test described by the company used sixty interface requests from another component library. OUI-1 produced fifty-five outputs accepted by its parser, versus twenty-three for DiffusionGemma. Parser acceptance measures structural validity, not whether the resulting interface is useful, accessible or visually well designed.