Stable Diffusion 3

Stable Diffusion 3, released in June 2024, is a Multimodal Diffusion Transformer trained with rectified flow matching, using three fixed text encoders (OpenCLIP-ViT/G, CLIP-ViT/L, and T5-XXL). The 2-billion-parameter Medium release was designed to run on consumer hardware while improving photorealism, complex prompt understanding, and typography.

It shipped under the Stability Community License, which permits free research and commercial use for entities under $1 million in annual revenue, with a paid enterprise license above that threshold. The release was widely seen as Stability AI's attempt to reclaim ground against closed image models, and the later 3.5 line refined the same architecture.