Safetensors
A safe, fast file format for storing model weights, designed to replace Python pickle files, which can run arbitrary code. It is the standard format for full-precision weights on Hugging Face.
Model weights have to be stored in some file format. The old default, Python’s pickle, can execute arbitrary code when loaded, which is a real security risk for files downloaded from the internet. Safetensors was designed to fix that: it stores only the tensors, loads quickly, and cannot run code.
It is now the standard for full-precision weights on Hugging Face, and what you download for a model you intend to run at full precision, fine-tune, or quantise yourself. For running quantised models locally you will more often meet GGUF or MLX; safetensors is the format the quantised versions are usually made from.