Unsloth is a local UI for training and running Gemma 4, Qwen3.6, DeepSeek, Kimi, GLM and other models. https://unsloth.ai/docs
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Daniel Han 35231d4ff4 inference: expose flex backend via UNSLOTH_FAST_INFERENCE=1
Setting UNSLOTH_FAST_INFERENCE=1 makes
FastLanguageModel.from_pretrained(..., fast_inference=True) return the
flex attention + paged KV + CUDA-graph backend instead of vLLM for
Qwen3, Llama-3, and Gemma-4-E2B-it. Default "0" keeps the existing vLLM
path.

The flex engine lives in a new unsloth.inference subpackage so the
FastLanguageModel wiring and any external caller can reach it without
going through scripts/. The user-facing GRPO notebooks for Qwen3,
Llama-3, and Gemma-4 run end-to-end with no code edits, just the env
var.

New subpackage

- unsloth/inference/flex_paged_attention.py: paged KV cache and
  block-mask helpers.
- unsloth/inference/flex_qwen3_llama.py: FlexInference for Qwen3 and
  Llama-3.2. tokenize() skips pre-populated input_ids so the engine
  can accept vLLM-style token-id prompts.
- unsloth/inference/flex_gemma4.py: FlexGemma4Inference. Text-shell
  extraction from Gemma4ForConditionalGeneration, per-layer-type
  sliding-window masks, KV sharing for layers 15-34.
- unsloth/inference/flex_engine.py: FlexEngine with the vLLM LLM
  surface. Arch dispatch, deep-copy of the HF model for colocate
  rollout so training forward stays intact, lazy pristine-base copy
  on first bind_peft_model, torch.amp.autocast("cuda", dtype=...)
  wrapping for the whole generate path, auto-tune for Triton block
  sizes per GPU capability and head_dim band. FA4 default OFF
  because the sm_100 FLASH backend crashes on short prompts; users
  can opt in with fa4_prefill=True.
- unsloth/inference/vllm_shim.py: LoRARequest, RequestOutput,
  CompletionOutput dataclasses plus save_lora / load_lora that
  mirror unsloth_zoo.vllm_utils line for line so the TRL GRPO patch
  sees the same attribute shape.

Wiring

- unsloth/models/loader.py: UNSLOTH_FAST_INFERENCE=1 bypasses the
  vLLM import guard in FastLanguageModel.from_pretrained (L356) and
  FastModel.from_pretrained (L982).
- unsloth/models/llama.py: the elif not fast_inference load branch
  now also handles the flex case, pops max_batch_size from kwargs
  (FlexEngine-only), snapshots the model into an inference copy
  BEFORE Unsloth's post-patch so flex-attention patching lands on a
  clean HF layout, and after the tokenizer loads constructs
  FlexEngine and attaches .vllm_engine / .fast_generate /
  .fast_generate_batches. FastLlamaModel.get_peft_model calls
  engine.bind_peft_model(peft) right after patch_peft_fast_inference
  so state_dict() reads the training LoRA tensors.
- unsloth/models/vision.py: same pattern for FastBaseModel. Gemma-4
  is allowed through the vision-model gate when the flex backend is
  selected; the engine extracts the text shell from
  Gemma4ForConditionalGeneration internally.
- unsloth/models/_utils.py: patch_peft_fast_inference picks
  unsloth.inference.vllm_shim.save_lora / load_lora when the engine
  is a FlexEngine, so the flex path never imports
  vllm.lora.request. fast_inference_setup skips patch_vllm() when
  UNSLOTH_FAST_INFERENCE=1.

Smoke tests (B200 sm_100)

- Qwen3-4B-Base bf16 (no LoRA and with get_peft_model LoRA)
- Qwen3-4B-Base fp16
- Llama-3.2-3B-Instruct bf16
- gemma-4-E2B-it bf16

all load through FastLanguageModel + UNSLOTH_FAST_INFERENCE=1 and
generate coherent completions.

Batched steady-state throughput via FastLanguageModel (autocast ON,
n_prompts=8 max_new_tokens=64 max_batch_size=16 max_seq_length=1024):

| Model                      | Flex CLI  | Integration | Delta |
|----------------------------|-----------|-------------|-------|
| Qwen3-4B-Base              | 819 tok/s | 595 tok/s   | -27%  |
| Llama-3.2-3B-Instruct      | 1163      | 1357        | +17%  |

Qwen3's regression is outside the 10% budget; most likely cause is
q_norm / k_norm being promoted to fp32 under autocast. Tracked for
a follow-up; the integration is functional and GRPO-usable today.

Note

The flex engine source files live here in unsloth/inference/. The
CLI benchmark drivers in scripts/benchmarks/ land in a separate PR
(#5108) which also carries the Gemma-4 and Llama-3 regression runs.
This PR depends only on what is already on main.

Known follow-ups

- FA4 on sm_100 needs a more robust enable rule before it can be
  default-on.
- Memory: 2x base-model VRAM without LoRA, 3x with LoRA.
- FlexEngine.sleep() / .wake_up() are no-op stubs; real CPU-offload
  parity with UNSLOTH_VLLM_STANDBY is a separate PR.
2026-04-21 11:59:47 +00:00
.github Update dependabot.yml (#4915) 2026-04-08 03:39:50 -07:00
images Add files via upload 2026-04-02 03:00:10 -07:00
scripts Add qwen3.6 script (#5084) 2026-04-17 01:21:30 -07:00
studio Studio: forward standard OpenAI tools / tool_choice on /v1/responses (Codex compat) (#5122) 2026-04-21 13:17:20 +04:00
tests inference: expose flex backend via UNSLOTH_FAST_INFERENCE=1 2026-04-21 11:59:47 +00:00
unsloth inference: expose flex backend via UNSLOTH_FAST_INFERENCE=1 2026-04-21 11:59:47 +00:00
unsloth_cli studio: stream export worker output into the export dialog (#4897) 2026-04-14 08:55:43 -07:00
.gitattributes EOL LF (unix line endings) normalization (#3478) 2025-10-17 16:22:42 -07:00
.gitignore Improve AI Assist: Update default model, model output parsing, logging, and dataset mapping UX (#4323) 2026-03-16 16:04:35 +04:00
.pre-commit-ci.yaml pre-commit CI config (#3565) 2025-11-07 14:44:18 -08:00
.pre-commit-config.yaml [pre-commit.ci] pre-commit autoupdate (#5004) 2026-04-14 09:49:18 -07:00
build.sh perf(studio): upgrade to Vite 8 + auto-install bun for faster frontend builds (#4522) 2026-03-25 04:27:41 -07:00
cli.py Rename cli/ to unsloth_cli/ to fix namespace collision with stringzilla (#4393) 2026-03-17 20:40:21 -07:00
CODE_OF_CONDUCT.md Update CODE_OF_CONDUCT.md 2025-10-25 19:31:05 -07:00
CONTRIBUTING.md Revert "Improve documentation on how to export model from Colab" 2026-03-13 22:38:41 -07:00
COPYING Rename cli/ to unsloth_cli/ to fix namespace collision with stringzilla (#4393) 2026-03-17 20:40:21 -07:00
install.ps1 Remove legacy venv Scripts entry from User PATH on upgrade (#5060) 2026-04-16 07:36:59 -07:00
install.sh Bump installer minimum to 2026.4.5 (#5041) 2026-04-15 08:23:41 -07:00
LICENSE Rename cli/ to unsloth_cli/ to fix namespace collision with stringzilla (#4393) 2026-03-17 20:40:21 -07:00
pyproject.toml Versioning 2026-04-16 12:06:10 -07:00
README.md Update README.md 2026-04-20 00:37:40 -07:00
unsloth-cli.py Merge pull request #3612 from Vangmay/feature/raw-text-dataprep 2026-01-08 03:38:15 -08:00

Unsloth logo

Unsloth Studio lets you run and train models locally.

FeaturesQuickstartNotebooksDocumentation


unsloth studio ui homepage

Get started

macOS, Linux, WSL:

curl -fsSL https://unsloth.ai/install.sh | sh

Windows:

irm https://unsloth.ai/install.ps1 | iex

Community:

Features

Unsloth Studio (Beta) lets you run and train text, audio, embedding, vision models on Windows, Linux and macOS.

Inference

Training

  • Train and RL 500+ models up to 2x faster with up to 70% less VRAM, with no accuracy loss.
  • Custom Triton and mathematical kernels. See some collabs we did with PyTorch and Hugging Face.
  • Data Recipes: Auto-create datasets from PDF, CSV, DOCX etc. Edit data in a visual-node workflow.
  • Reinforcement Learning (RL): The most efficient RL library, using 80% less VRAM for GRPO, FP8 etc.
  • Supports full fine-tuning, RL, pretraining, 4-bit, 16-bit and, FP8 training.
  • Observability: Monitor training live, track loss and GPU usage and customize graphs.
  • Multi-GPU training is supported, with major improvements coming soon.

📥 Install

Unsloth can be used in two ways: through Unsloth Studio, the web UI, or through Unsloth Core, the code-based version. Each has different requirements.

Unsloth Studio (web UI)

Unsloth Studio (Beta) works on Windows, Linux, WSL and macOS.

  • CPU: Supported for Chat and Data Recipes currently
  • NVIDIA: Training works on RTX 30/40/50, Blackwell, DGX Spark, Station and more
  • macOS: Currently supports chat and Data Recipes. MLX training is coming very soon
  • AMD: Chat + Data works. Train with Unsloth Core. Studio support is out soon.
  • Coming soon: Training support for Apple MLX, AMD, and Intel.
  • Multi-GPU: Available now, with a major upgrade on the way

macOS, Linux, WSL:

curl -fsSL https://unsloth.ai/install.sh | sh

Windows:

irm https://unsloth.ai/install.ps1 | iex

Launch

unsloth studio -H 0.0.0.0 -p 8888

Update

To update, use the same install commands as above. Or run (does not work on Windows):

unsloth studio update

Docker

Use our Docker image unsloth/unsloth container. Run:

docker run -d -e JUPYTER_PASSWORD="mypassword" \
  -p 8888:8888 -p 8000:8000 -p 2222:22 \
  -v $(pwd)/work:/workspace/work \
  --gpus all \
  unsloth/unsloth

Developer, Nightly, Uninstall

To see developer, nightly and uninstallation etc. instructions, see advanced installation.

Unsloth Core (code-based)

Linux, WSL:

curl -LsSf https://astral.sh/uv/install.sh | sh
uv venv unsloth_env --python 3.13
source unsloth_env/bin/activate
uv pip install unsloth --torch-backend=auto

Windows:

winget install -e --id Python.Python.3.13
winget install --id=astral-sh.uv  -e
uv venv unsloth_env --python 3.13
.\unsloth_env\Scripts\activate
uv pip install unsloth --torch-backend=auto

For Windows, pip install unsloth works only if you have PyTorch installed. Read our Windows Guide. You can use the same Docker image as Unsloth Studio.

AMD, Intel:

For RTX 50x, B200, 6000 GPUs: uv pip install unsloth --torch-backend=auto. Read our guides for: Blackwell and DGX Spark.
To install Unsloth on AMD and Intel GPUs, follow our AMD Guide and Intel Guide.

📒 Free Notebooks

Train for free with our notebooks. You can use our new free Unsloth Studio notebook to run and train models for free in a web UI. Read our guide. Add dataset, run, then deploy your trained model.

Model Free Notebooks Performance Memory use
Gemma 4 (E2B) ▶️ Start for free 1.5x faster 50% less
Qwen3.5 (4B) ▶️ Start for free 1.5x faster 60% less
gpt-oss (20B) ▶️ Start for free 2x faster 70% less
Qwen3.5 GSPO ▶️ Start for free 2x faster 70% less
gpt-oss (20B): GRPO ▶️ Start for free 2x faster 80% less
Qwen3: Advanced GRPO ▶️ Start for free 2x faster 70% less
embeddinggemma (300M) ▶️ Start for free 2x faster 20% less
Mistral Ministral 3 (3B) ▶️ Start for free 1.5x faster 60% less
Llama 3.1 (8B) Alpaca ▶️ Start for free 2x faster 70% less
Llama 3.2 Conversational ▶️ Start for free 2x faster 70% less
Orpheus-TTS (3B) ▶️ Start for free 1.5x faster 50% less

🦥 Unsloth News

  • Qwen3.6: Qwen3.6-35B-A3B can now be trained and run in Unsloth Studio. Blog
  • Gemma 4: Run and train Googles new models directly in Unsloth. Blog
  • Introducing Unsloth Studio: our new web UI for running and training LLMs. Blog
  • Qwen3.5 - 0.8B, 2B, 4B, 9B, 27B, 35-A3B, 112B-A10B are now supported. Guide + notebooks
  • Train MoE LLMs 12x faster with 35% less VRAM - DeepSeek, GLM, Qwen and gpt-oss. Blog
  • Embedding models: Unsloth now supports ~1.8-3.3x faster embedding fine-tuning. BlogNotebooks
  • New 7x longer context RL vs. all other setups, via our new batching algorithms. Blog
  • New RoPE & MLP Triton Kernels & Padding Free + Packing: 3x faster training & 30% less VRAM. Blog
  • 500K Context: Training a 20B model with >500K context is now possible on an 80GB GPU. Blog
  • FP8 & Vision RL: You can now do FP8 & VLM GRPO on consumer GPUs. FP8 BlogVision RL
  • gpt-oss by OpenAI: Read our RL blog, Flex Attention blog and Guide.

📥 Advanced Installation

The below advanced instructions are for Unsloth Studio. For Unsloth Core advanced installation, view our docs.

Developer installs: macOS, Linux, WSL:

git clone https://github.com/unslothai/unsloth
cd unsloth
./install.sh --local
unsloth studio -H 0.0.0.0 -p 8888

Then to update :

unsloth studio update

Developer installs: Windows PowerShell:

git clone https://github.com/unslothai/unsloth.git
cd unsloth
Set-ExecutionPolicy -Scope Process -ExecutionPolicy Bypass
.\install.ps1 --local
unsloth studio -H 0.0.0.0 -p 8888

Then to update :

unsloth studio update

Nightly: MacOS, Linux, WSL:

git clone https://github.com/unslothai/unsloth
cd unsloth
git checkout nightly
./install.sh --local
unsloth studio -H 0.0.0.0 -p 8888

Then to launch every time:

unsloth studio -H 0.0.0.0 -p 8888

Nightly: Windows:

Run in Windows Powershell:

git clone https://github.com/unslothai/unsloth.git
cd unsloth
git checkout nightly
Set-ExecutionPolicy -Scope Process -ExecutionPolicy Bypass
.\install.ps1 --local
unsloth studio -H 0.0.0.0 -p 8888

Then to launch every time:

unsloth studio -H 0.0.0.0 -p 8888

Uninstall

You can uninstall Unsloth Studio by deleting its install folder usually located under $HOME/.unsloth/studio on Mac/Linux/WSL and %USERPROFILE%\.unsloth\studio on Windows. Using the rm -rf commands will delete everything, including your history, cache:

  • MacOS, WSL, Linux: rm -rf ~/.unsloth/studio
  • Windows (PowerShell): Remove-Item -Recurse -Force "$HOME\.unsloth\studio"

For more info, see our docs.

Deleting model files

You can delete old model files either from the bin icon in model search or by removing the relevant cached model folder from the default Hugging Face cache directory. By default, HF uses:

  • MacOS, Linux, WSL: ~/.cache/huggingface/hub/
  • Windows: %USERPROFILE%\.cache\huggingface\hub\
Type Links
  Discord Join Discord server
  r/unsloth Reddit Join Reddit community
📚 Documentation & Wiki Read Our Docs
  Twitter (aka X) Follow us on X
🔮 Our Models Unsloth Catalog
✍️ Blog Read our Blogs

Citation

You can cite the Unsloth repo as follows:

@software{unsloth,
  author = {Daniel Han, Michael Han and Unsloth team},
  title = {Unsloth},
  url = {https://github.com/unslothai/unsloth},
  year = {2023}
}

If you trained a model with 🦥Unsloth, you can use this cool sticker!  

License

Unsloth uses a dual-licensing model of Apache 2.0 and AGPL-3.0. The core Unsloth package remains licensed under Apache 2.0, while certain optional components, such as the Unsloth Studio UI are licensed under the open-source license AGPL-3.0.

This structure helps support ongoing Unsloth development while keeping the project open source and enabling the broader ecosystem to continue growing.

Thank You to

  • The llama.cpp library that lets users run and save models with Unsloth
  • The Hugging Face team and their libraries: transformers and TRL
  • The Pytorch and Torch AO team for their contributions
  • NVIDIA for their NeMo DataDesigner library and their contributions
  • And of course for every single person who has contributed or has used Unsloth!