Alibaba NLP releases UEmbed-4B, a unified sparse and dense multimodal embedding model

Alibaba NLP has released UEmbed-4B, a decoder-only multimodal embedding model built on Qwen3.5 4B that outputs both dense and sparse embeddings from one forward pass.

It handles text, image, video, and mixed-modal inputs for retrieval and visual-document search, and sparse activations map to vocabulary terms usable with inverted indexes.

The model is available on Hugging Face in a family that also includes 2B and 9B variants.