.ckpt (PyTorch Checkpoint), which is the standard format used by early versions of Stable Diffusion (v1.4/v1.5) for distributing model weights.
Models like this are typically optimized to handle specific aesthetic tags and intricate details common in modern anime art styles that base models often struggle with. f99.ckpt
The "WD" in the name suggests it is a version of Waifu Diffusion , a popular open-source model trained on the Danbooru dataset to improve anime character rendering and tag comprehension. .ckpt (PyTorch Checkpoint)