Instructions to use QUASAR-QAT/Qwen3.8-27B-QUASAR-NVFP4 with libraries, inference providers, notebooks, and local apps. Follow these links to get started.

Libraries

How to use QUASAR-QAT/Qwen3.8-27B-QUASAR-NVFP4 with Transformers:

# Use a pipeline as a high-level helper
from transformers import pipeline

pipe = pipeline("image-text-to-text", model="QUASAR-QAT/Qwen3.8-27B-QUASAR-NVFP4")
messages = [
    {
        "role": "user",
        "content": [
            {"type": "image", "url": "https://huggingface.co/datasets/huggingface/documentation-images/resolve/main/p-blog/candy.JPG"},
            {"type": "text", "text": "What animal is on the candy?"}
        ]
    },
]
pipe(text=messages)

# Load model directly
from transformers import AutoProcessor, AutoModelForMultimodalLM

processor = AutoProcessor.from_pretrained("QUASAR-QAT/Qwen3.8-27B-QUASAR-NVFP4")
model = AutoModelForMultimodalLM.from_pretrained("QUASAR-QAT/Qwen3.8-27B-QUASAR-NVFP4", device_map="auto")
messages = [
    {
        "role": "user",
        "content": [
            {"type": "image", "url": "https://huggingface.co/datasets/huggingface/documentation-images/resolve/main/p-blog/candy.JPG"},
            {"type": "text", "text": "What animal is on the candy?"}
        ]
    },
]
inputs = processor.apply_chat_template(
	messages,
	add_generation_prompt=True,
	tokenize=True,
	return_dict=True,
	return_tensors="pt",
).to(model.device)

outputs = model.generate(**inputs, max_new_tokens=40)
print(processor.decode(outputs[0][inputs["input_ids"].shape[-1]:]))

Notebooks
Google Colab
Kaggle
Local Apps Settings

vLLM

How to use QUASAR-QAT/Qwen3.8-27B-QUASAR-NVFP4 with vLLM:

Install from pip and serve model

# Install vLLM from pip:
pip install vllm
# Start the vLLM server:
vllm serve "QUASAR-QAT/Qwen3.8-27B-QUASAR-NVFP4"
# Call the server using curl (OpenAI-compatible API):
curl -X POST "http://localhost:8000/v1/chat/completions" \
	-H "Content-Type: application/json" \
	--data '{
		"model": "QUASAR-QAT/Qwen3.8-27B-QUASAR-NVFP4",
		"messages": [
			{
				"role": "user",
				"content": [
					{
						"type": "text",
						"text": "Describe this image in one sentence."
					},
					{
						"type": "image_url",
						"image_url": {
							"url": "https://cdn.britannica.com/61/93061-050-99147DCE/Statue-of-Liberty-Island-New-York-Bay.jpg"
						}
					}
				]
			}
		]
	}'

Use Docker

docker model run hf.co/QUASAR-QAT/Qwen3.8-27B-QUASAR-NVFP4

SGLang

How to use QUASAR-QAT/Qwen3.8-27B-QUASAR-NVFP4 with SGLang:

Install from pip and serve model

# Install SGLang from pip:
pip install sglang
# Start the SGLang server:
python3 -m sglang.launch_server \
    --model-path "QUASAR-QAT/Qwen3.8-27B-QUASAR-NVFP4" \
    --host 0.0.0.0 \
    --port 30000
# Call the server using curl (OpenAI-compatible API):
curl -X POST "http://localhost:30000/v1/chat/completions" \
	-H "Content-Type: application/json" \
	--data '{
		"model": "QUASAR-QAT/Qwen3.8-27B-QUASAR-NVFP4",
		"messages": [
			{
				"role": "user",
				"content": [
					{
						"type": "text",
						"text": "Describe this image in one sentence."
					},
					{
						"type": "image_url",
						"image_url": {
							"url": "https://cdn.britannica.com/61/93061-050-99147DCE/Statue-of-Liberty-Island-New-York-Bay.jpg"
						}
					}
				]
			}
		]
	}'

Use Docker images

docker run --gpus all \
    --shm-size 32g \
    -p 30000:30000 \
    -v ~/.cache/huggingface:/root/.cache/huggingface \
    --env "HF_TOKEN=<secret>" \
    --ipc=host \
    lmsysorg/sglang:latest \
    python3 -m sglang.launch_server \
        --model-path "QUASAR-QAT/Qwen3.8-27B-QUASAR-NVFP4" \
        --host 0.0.0.0 \
        --port 30000
# Call the server using curl (OpenAI-compatible API):
curl -X POST "http://localhost:30000/v1/chat/completions" \
	-H "Content-Type: application/json" \
	--data '{
		"model": "QUASAR-QAT/Qwen3.8-27B-QUASAR-NVFP4",
		"messages": [
			{
				"role": "user",
				"content": [
					{
						"type": "text",
						"text": "Describe this image in one sentence."
					},
					{
						"type": "image_url",
						"image_url": {
							"url": "https://cdn.britannica.com/61/93061-050-99147DCE/Statue-of-Liberty-Island-New-York-Bay.jpg"
						}
					}
				]
			}
		]
	}'

Docker Model Runner
How to use QUASAR-QAT/Qwen3.8-27B-QUASAR-NVFP4 with Docker Model Runner:
```
docker model run hf.co/QUASAR-QAT/Qwen3.8-27B-QUASAR-NVFP4
```

Qwen3.8-27B NVFP4, trained with QUASAR

19.7 GB · 496/496 transformer linears in NVFP4 (W4A4) · 0.909 GPQA-Diamond vs. 0.914 BF16 · serves directly with vLLM.

Among the public NVFP4 builds compared below, QUASAR is both the smallest and the highest-scoring: 90.9 GPQA-Diamond and 100% AIME'26.

Independent evaluation: A third-party NVFP4 shootout on the official Qwen3.8-27B repo compares QUASAR against other public NVFP4 checkpoints under the same evaluation and serving setup.

Smaller sibling — Qwen3.5-4B: W4A16 / vLLM · W4A4 / Blackwell · Q4_0 GGUF / llama.cpp · collection · paper

More QUASAR checkpoints: Gemma 4 collection · Muse-Glimmer collection · paper.

QUASAR-QAT/Qwen3.8-27B-QUASAR-NVFP4 is a 4-bit NVFP4 version of Qwen/Qwen3.8-27B, produced with QUASAR, a quantization-aware training (QAT) method.

QUASAR trains the NVFP4 weights directly against the frozen BF16 model, then exports standard NVFP4 weights with no custom inference path. This lets us quantize all 496 transformer linears—including attention and gated delta-net—to NVFP4 while preserving near-BF16 quality: the smallest of the compared public NVFP4 builds, while scoring highest among them on both GPQA-Diamond and AIME'26.

📄 Paper: QUASAR: Lowering the Loss Floor of Quantization-Aware Training with Loss-Aware Reconstruction

How to run

Compatible with vLLM, with no conversion step:

pip install "vllm>=0.27"

vllm serve QUASAR-QAT/Qwen3.8-27B-QUASAR-NVFP4 \
  --max-model-len 262144 \
  --gpu-memory-utilization 0.85 \
  --speculative-config '{"method": "mtp", "num_speculative_tokens": 2}'

On a 32 GB card such as an RTX 5090, lower the context to --max-model-len 65536.

Requires an NVIDIA GPU with FP4 support (Blackwell, compute capability 10.0+).

Quality and size comparison

Two other public NVFP4 builds of this model, evaluated under the same setup (GPQA-Diamond: 2 runs, n=396; AIME'26: 3 repeats, n=90). Bold = best among the NVFP4 builds.

Model	Size	NVFP4 linears	GPQA-D	AIME'26
QUASAR (this model)	19.7 GB	496/496	90.91	100.0
BF16 original	55.6 GB	—	91.41	100.0
Unsloth NVFP4	23.4 GB	168/496	89.39	97.78
Inferact NVFP4	26.4 GB	304/496	87.63	96.67

Training

One epoch of loss-aware NVFP4 quantization-aware distillation against the frozen BF16 teacher: global batch size 32, learning rate 1e-6, 2446 steps.

Citation

arxiv.org/abs/2608.13966

@article{counathe2026quasar,
  title={QUASAR: Lowering the Loss Floor of Quantization-Aware Training with Loss-Aware Reconstruction},
  author={Counathe, Vincent and Athiwaratkun, Ben and De Sa, Christopher and Zhang, Tianyi},
  journal={arXiv preprint arXiv:2608.13966},
  year={2026}
}