Image-Text-to-Text
Transformers
Safetensors
English
Chinese
multilingual
step3p5v
text-generation
stepfun
step-5
Mixture of Experts
mixture-of-experts
agentic
coding
software-engineering
long-context
1m-context
multimodal
image
video
sparse-attention
gqa
financial-analysis
deep-research
tool-calling
parallel-tool-calling
json-schema
conversational
custom_code
Instructions to use SHSLab/Step-5-Preview-BF16 with libraries, inference providers, notebooks, and local apps. Follow these links to get started.
- Libraries
- Transformers
How to use SHSLab/Step-5-Preview-BF16 with Transformers:
# Use a pipeline as a high-level helper from transformers import pipeline pipe = pipeline("image-text-to-text", model="SHSLab/Step-5-Preview-BF16", trust_remote_code=True) 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 AutoModelForCausalLM model = AutoModelForCausalLM.from_pretrained("SHSLab/Step-5-Preview-BF16", trust_remote_code=True, device_map="auto") - Notebooks
- Google Colab
- Kaggle
- Local Apps Settings
- vLLM
How to use SHSLab/Step-5-Preview-BF16 with vLLM:
Install from pip and serve model
# Install vLLM from pip: pip install vllm # Start the vLLM server: vllm serve "SHSLab/Step-5-Preview-BF16" # Call the server using curl (OpenAI-compatible API): curl -X POST "http://localhost:8000/v1/chat/completions" \ -H "Content-Type: application/json" \ --data '{ "model": "SHSLab/Step-5-Preview-BF16", "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/SHSLab/Step-5-Preview-BF16
- SGLang
How to use SHSLab/Step-5-Preview-BF16 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 "SHSLab/Step-5-Preview-BF16" \ --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": "SHSLab/Step-5-Preview-BF16", "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 "SHSLab/Step-5-Preview-BF16" \ --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": "SHSLab/Step-5-Preview-BF16", "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 SHSLab/Step-5-Preview-BF16 with Docker Model Runner:
docker model run hf.co/SHSLab/Step-5-Preview-BF16
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| 1 |
---
|
| 2 |
language:
|
| 3 |
+
- en
|
| 4 |
- zh
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| 5 |
+
- multilingual
|
| 6 |
+
license: other
|
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+
license_name: stepfun-community-license
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+
license_link: https://huggingface.co/SHSLab/Step-5-Preview-BF16/blob/main/LICENSE
|
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+
library_name: transformers
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+
pipeline_tag: text-generation
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+
tags:
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+
- stepfun
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| 13 |
+
- step-5
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| 14 |
+
- moe
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| 15 |
+
- mixture-of-experts
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| 16 |
+
- agentic
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| 17 |
+
- coding
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| 18 |
+
- software-engineering
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| 19 |
+
- long-context
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| 20 |
+
- 1m-context
|
| 21 |
+
- multimodal
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| 22 |
+
- text-generation
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| 23 |
+
- image
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| 24 |
+
- video
|
| 25 |
+
- sparse-attention
|
| 26 |
+
- gqa
|
| 27 |
+
- financial-analysis
|
| 28 |
+
- deep-research
|
| 29 |
+
- tool-calling
|
| 30 |
+
- parallel-tool-calling
|
| 31 |
+
- json-schema
|
| 32 |
+
base_model: SHSLab/Step-5-Preview-BF16
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| 33 |
---
|
| 34 |
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| 35 |
+
# Step-5-Preview
|
| 36 |
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| 37 |
+
<div align="center">
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| 38 |
+
<img src="https://raw.githubusercontent.com/stepfun-ai/Step-5-Preview/main/assets/step5_banner.png" alt="Step 5 Preview Banner" width="100%">
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| 39 |
+
</div>
|
| 40 |
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| 41 |
+
<div align="center">
|
| 42 |
+
|
| 43 |
+
[](https://huggingface.co/SHSLab)
|
| 44 |
+
[](https://github.com/stepfun-ai)
|
| 45 |
+
[](https://discord.gg/stepfun)
|
| 46 |
+
[](https://huggingface.co/SHSLab/Step-5-Preview-BF16/blob/main/LICENSE)
|
| 47 |
+
[]()
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| 48 |
+
[]()
|
| 49 |
+
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| 50 |
+
</div>
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| 51 |
+
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| 52 |
+
<div style="background-color: #e6f7ff; padding: 16px; border-radius: 8px; border-left: 6px solid #1890ff; margin: 20px 0;">
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| 53 |
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<strong>🔥 Step-5-Preview is now available!</strong><br>
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| 54 |
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We are excited to release <strong>Step-5-Preview</strong>, our flagship foundation model for real-world agentic work.
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| 55 |
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It is a 600B-parameter sparse Mixture-of-Experts model with 27B active parameters, a 1M-token context window,
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and native support for text, image, and video inputs.
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<br><br>
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| 58 |
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<strong>Weights are available now</strong> on Hugging Face.
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| 59 |
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Try it via our API, or deploy locally with vLLM / SGLang.
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| 60 |
+
</div>
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| 61 |
+
|
| 62 |
+
---
|
| 63 |
+
|
| 64 |
+
## 📖 Table of Contents
|
| 65 |
+
|
| 66 |
+
- [Introduction](#-introduction)
|
| 67 |
+
- [Key Features](#-key-features)
|
| 68 |
+
- [Model Architecture](#-model-architecture)
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| 69 |
+
- [Model Specifications](#-model-specifications)
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| 70 |
+
- [Benchmark Results](#-benchmark-results)
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| 71 |
+
- [Agentic Capabilities](#-agentic-capabilities)
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| 72 |
+
- [Quickstart](#-quickstart)
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| 73 |
+
- [Deployment](#-deployment)
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| 74 |
+
- [Evaluation](#-evaluation)
|
| 75 |
+
- [Citation](#-citation)
|
| 76 |
+
- [License](#-license)
|
| 77 |
+
- [Contact](#-contact)
|
| 78 |
+
|
| 79 |
+
---
|
| 80 |
+
|
| 81 |
+
## 🚀 Introduction
|
| 82 |
+
|
| 83 |
+
**Step-5-Preview** is StepFun's flagship foundation model, designed from the ground up for **real-world agentic tasks**.
|
| 84 |
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It targets professional domains such as **AI coding, software engineering, professional knowledge work, and financial analysis**.
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| 85 |
+
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| 86 |
+
StepFun's core philosophy for Step 5 is the **"Pareto Frontier"** — achieving the optimal balance between intelligence and cost.
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| 87 |
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While previous scaling efforts focused on trading more compute for stronger intelligence, the next phase requires improving the
|
| 88 |
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**efficiency of converting compute into intelligence**.
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| 89 |
+
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| 90 |
+
<div style="background-color: #fff7e6; padding: 16px; border-radius: 8px; border-left: 6px solid #fa8c16; margin: 20px 0;">
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| 91 |
+
<strong>💡 Why Step 5 Preview?</strong><br>
|
| 92 |
+
• <strong>600B total parameters, only 27B active</strong> — near-frontier performance at a fraction of the compute.<br>
|
| 93 |
+
• <strong>1M-token context window</strong> without proportional cost increases.<br>
|
| 94 |
+
• <strong>Competitive benchmark scores</strong> against models with 3–5× more parameters.<br>
|
| 95 |
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• <strong>Built for agents</strong> — long-horizon reasoning, tool use, and autonomous execution.
|
| 96 |
+
</div>
|
| 97 |
+
|
| 98 |
+
---
|
| 99 |
+
|
| 100 |
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## ✨ Key Features
|
| 101 |
+
|
| 102 |
+
<div align="center">
|
| 103 |
+
<img src="https://raw.githubusercontent.com/stepfun-ai/Step-5-Preview/main/assets/features.png" alt="Key Features" width="90%">
|
| 104 |
+
</div>
|
| 105 |
+
|
| 106 |
+
- **Sparse Mixture-of-Experts (MoE):** 600B total parameters, 27B active per token (~4.5% sparsity).
|
| 107 |
+
- **1M-Token Context Window:** Equivalent to ~1,500 A4 pages, enabled by Sparse GQA.
|
| 108 |
+
- **Multimodal Input:** Text, image, and video (MP4, QuickTime, Matroska; ≤128 MB; ≤5 min recommended).
|
| 109 |
+
- **Configurable Reasoning Effort:** `low`, `medium`, `high` / `xhigh`.
|
| 110 |
+
- **Parallel Tool Calling:** Natively supported for agentic workflows.
|
| 111 |
+
- **Strict JSON Schema Output:** Reliable integration into structured systems.
|
| 112 |
+
- **OpenAI-Compatible API:** Available via Step API and third-party gateways.
|
| 113 |
+
- **Open Weights:** BF16 checkpoint available now.
|
| 114 |
+
|
| 115 |
+
---
|
| 116 |
+
|
| 117 |
+
## 🏗️ Model Architecture
|
| 118 |
+
|
| 119 |
+
<div align="center">
|
| 120 |
+
<img src="https://raw.githubusercontent.com/stepfun-ai/Step-5-Preview/main/assets/architecture.png" alt="Step 5 Architecture" width="85%">
|
| 121 |
+
</div>
|
| 122 |
+
|
| 123 |
+
### 92-Layer "Narrow but Deep" Design
|
| 124 |
+
|
| 125 |
+
Step-5-Preview uses a **92-layer Transformer** with a narrow-deep configuration. This design is specifically intended to create
|
| 126 |
+
**longer information propagation paths** for implicit multi-hop reasoning during long prefill operations.
|
| 127 |
+
|
| 128 |
+
### Sparse Grouped-Query Attention (GQA) with Block-Wise Token Merging
|
| 129 |
+
|
| 130 |
+
To handle the 1M-token context window efficiently, Step-5-Preview introduces **Sparse GQA with block-wise token merging**.
|
| 131 |
+
This mechanism uses sparse indexing to select only historical information relevant to the current task, reducing the number of tokens
|
| 132 |
+
that actually enter attention computation. StepFun states this cuts indexer and top-k selection costs to approximately
|
| 133 |
+
**one-eighth** of a denser baseline.
|
| 134 |
+
|
| 135 |
+
<div style="background-color: #f6ffed; padding: 16px; border-radius: 8px; border-left: 6px solid #52c41a; margin: 20px 0;">
|
| 136 |
+
<strong>⚡ Efficiency-First Scaling</strong><br>
|
| 137 |
+
Step 5 Preview achieves near-frontier performance with <strong>600B total parameters</strong> but only
|
| 138 |
+
<strong>27B active per token</strong>. This is the core of StepFun's efficiency-first philosophy.
|
| 139 |
+
</div>
|
| 140 |
+
|
| 141 |
+
---
|
| 142 |
+
|
| 143 |
+
## 📋 Model Specifications
|
| 144 |
+
|
| 145 |
+
| Category | Specification |
|
| 146 |
+
|:---|:---|
|
| 147 |
+
| **Model Name** | Step-5-Preview |
|
| 148 |
+
| **Developer** | StepFun |
|
| 149 |
+
| **Architecture** | Sparse Mixture-of-Experts (MoE) |
|
| 150 |
+
| **Total Parameters** | 600B |
|
| 151 |
+
| **Active Parameters** | 27B per token (~4.5% sparsity) |
|
| 152 |
+
| **Layers** | 92 (narrow-deep Transformer) |
|
| 153 |
+
| **Context Window** | 1,000,000 tokens |
|
| 154 |
+
| **Attention** | Sparse GQA with block-wise token merging |
|
| 155 |
+
| **Input Modalities** | Text, Image, Video |
|
| 156 |
+
| **Output Modalities** | Text |
|
| 157 |
+
| **Video Formats** | MP4, QuickTime, Matroska (≤128 MB, ≤5 min recommended) |
|
| 158 |
+
| **Reasoning Effort** | `low` / `medium` / `high` (`xhigh`) |
|
| 159 |
+
| **Tool Calling** | Parallel, strict JSON schema |
|
| 160 |
+
| **Intelligence Index** | 44 (Artificial Analysis v4.3.2) |
|
| 161 |
+
| **Open Weights** | BF16 checkpoint available now |
|
| 162 |
+
| **API Availability** | Immediate (OpenAI-compatible) |
|
| 163 |
+
|
| 164 |
+
---
|
| 165 |
+
|
| 166 |
+
## 📊 Benchmark Results
|
| 167 |
+
|
| 168 |
+
### Artificial Analysis Intelligence Index
|
| 169 |
+
|
| 170 |
+
<div align="center">
|
| 171 |
+
<img src="https://raw.githubusercontent.com/stepfun-ai/Step-5-Preview/main/assets/intelligence_index.png" alt="Intelligence Index" width="80%">
|
| 172 |
+
</div>
|
| 173 |
+
|
| 174 |
+
**Overall Score: 44** (Intelligence Index v4.3.2, recalibrated September 7, 2026)
|
| 175 |
+
|
| 176 |
+
This places Step-5-Preview among the **top three open-weight models globally**, on par with models like
|
| 177 |
+
Kimi K3 Max (approximately 5× larger at 2.8T parameters) and Qwen3.8 Max. The index covers 10 evaluations including
|
| 178 |
+
AA-Briefcase, GDPval-AA v2, Terminal-Bench 4.0, SciCode, and Humanity's Last Exam.
|
| 179 |
+
|
| 180 |
+
### Detailed Benchmark Scores
|
| 181 |
+
|
| 182 |
+
<div style="background-color: #fafafa; padding: 16px; border-radius: 8px; border: 1px solid #e8e8e8; margin: 20px 0;">
|
| 183 |
+
|
| 184 |
+
| Benchmark | Step-5-Preview (High) | Kimi K3 (Max) | GLM-5.3 (Max) | Claude Opus 5 (Max) | GPT-6 Astra (Max) |
|
| 185 |
+
|:---|:---|:---|:---|:---|:---|
|
| 186 |
+
| **DeepSWE v1.1** | **67.7** | 67.5 | 66.9 | 74.0 | 74.1 |
|
| 187 |
+
| **StepCodeBench** | **49.0** | 43.9 | 40.2 | 63.9 | 61.0 |
|
| 188 |
+
| **ProgramBench** | **80.5** | 77.8 | 72.0 | 82.3 | 85.4 |
|
| 189 |
+
| **Terminal-Bench v4** | 33.3 | 12.6 | 41.9 | 52.3 | 57.9 |
|
| 190 |
+
| **Agents' Last Exam (ALE-CLI)** | **29.5** | 27.6 | 28.6 | 28.6 | 33.3 |
|
| 191 |
+
| **GDPval-AA v2** | 1571 | 1548 | 1634 | 1735 | 1580 |
|
| 192 |
+
| **FrontierFinance** | **66.4** | 62.6 | 64.1 | 69.7 | 55.0 |
|
| 193 |
+
| **DRACO** | **83.3** | 78.5 | 82.3 | 87.6 | 76.8 |
|
| 194 |
+
|
| 195 |
+
</div>
|
| 196 |
+
|
| 197 |
+
<details>
|
| 198 |
+
<summary><strong>📝 Benchmark Methodology Notes</strong> (click to expand)</summary>
|
| 199 |
+
|
| 200 |
+
- **DeepSWE v1.1** was evaluated using the SWE-agent harness with `temperature=1.0` and `top_p=0.95`.
|
| 201 |
+
- **GDPval-AA v2** results are from Artificial Analysis as of September 19, 2026.
|
| 202 |
+
- **StepCodeBench** achieved **49.0% avg@4**.
|
| 203 |
+
- **SciCode**: Step-5-Preview scored higher than Kimi K3.
|
| 204 |
+
- **Output Speed**: 99.8 tokens/sec (GLM-5.3: 72.1 tokens/sec).
|
| 205 |
+
- **Time to First Token**: 2.96 seconds (GLM-5.3: 2.99s; Claude Opus 5: 56.84s at max effort).
|
| 206 |
+
- **Terminal-Bench 4.0 vs Kimi K3**: 33.3% vs ~12.6%.
|
| 207 |
+
- **Terminal-Bench 4.0 vs DeepSeek V4.1 Flash**: 33.3% vs 26.8%.
|
| 208 |
+
|
| 209 |
+
</details>
|
| 210 |
+
|
| 211 |
+
### Benchmark Takeaways
|
| 212 |
+
|
| 213 |
+
<div style="background-color: #f0f5ff; padding: 16px; border-radius: 8px; border-left: 6px solid #2f54eb; margin: 20px 0;">
|
| 214 |
+
<strong>🧠 Coding & Software Engineering</strong><br>
|
| 215 |
+
Step-5-Preview <strong>leads all open-weight models</strong> on DeepSWE v1.1 and StepCodeBench, surpassing Kimi K3 and GLM-5.3.
|
| 216 |
+
It trails only the larger closed-source models (Claude Opus 5 and GPT-6 Astra).
|
| 217 |
+
</div>
|
| 218 |
+
|
| 219 |
+
<div style="background-color: #fff1f0; padding: 16px; border-radius: 8px; border-left: 6px solid #f5222d; margin: 20px 0;">
|
| 220 |
+
<strong>🤖 Agentic Tasks</strong><br>
|
| 221 |
+
Strong performance on Terminal-Bench 4.0 (<strong>33.3%</strong>) and Agents' Last Exam (ALE-CLI) (<strong>29.5%</strong>).
|
| 222 |
+
Terminal-Bench score is <strong>2.6× higher than Kimi K3</strong> and <strong>1.24× higher than DeepSeek V4.1 Flash</strong>.
|
| 223 |
+
</div>
|
| 224 |
+
|
| 225 |
+
<div style="background-color: #fcffe6; padding: 16px; border-radius: 8px; border-left: 6px solid #a0d911; margin: 20px 0;">
|
| 226 |
+
<strong>💰 Financial & Deep Research</strong><br>
|
| 227 |
+
Highly competitive on FrontierFinance and DRACO, nearly matching top closed-source models like Claude Opus 5.
|
| 228 |
+
On FrontierFinance, it outperforms both Kimi K3 and GLM-5.3 by a significant margin.
|
| 229 |
+
</div>
|
| 230 |
+
|
| 231 |
+
---
|
| 232 |
+
|
| 233 |
+
## 🤖 Agentic Capabilities
|
| 234 |
+
|
| 235 |
+
<div align="center">
|
| 236 |
+
<img src="https://raw.githubusercontent.com/stepfun-ai/Step-5-Preview/main/assets/agentic_workflow.png" alt="Agentic Workflow" width="90%">
|
| 237 |
+
</div>
|
| 238 |
+
|
| 239 |
+
### 24-Hour Autonomous GPU Kernel Optimization
|
| 240 |
+
|
| 241 |
+
In a landmark demonstration of sustained agentic execution, Step-5-Preview was tasked with **autonomously optimizing an H100 GPU kernel for up to 24 consecutive hours**. The model:
|
| 242 |
+
|
| 243 |
+
- Independently modified code
|
| 244 |
+
- Ran tests and compared results
|
| 245 |
+
- Iterated based on performance outcomes
|
| 246 |
+
- **Reached 508 TFLOPS after approximately 22 hours**
|
| 247 |
+
|
| 248 |
+
For comparison, **Claude Opus 5 achieved 493 TFLOPS** in the same experiment. This demonstrates Step-5-Preview's ability to sustain productive work over extended periods without human intervention.
|
| 249 |
+
|
| 250 |
+
### Automated Post-Training Experiments
|
| 251 |
+
|
| 252 |
+
In another 24-hour experiment, Step-5-Preview autonomously improved the accuracy of **Qwen3-30B-A3B on AIME24 from 53.3% to 60%** through automated post-training experiments. This showcases the model's capacity for self-directed research and optimization.
|
| 253 |
+
|
| 254 |
+
### Real-World Application Demonstrations
|
| 255 |
+
|
| 256 |
+
StepFun demonstrated the model's capabilities across several complex, real-world projects:
|
| 257 |
+
|
| 258 |
+
- **ESP32 Development Board Modifications:** Executed development tasks for over 3 hours, demonstrating hardware programming capabilities.
|
| 259 |
+
- **Front-End Design with 3D Asset Generation:** Full-stack development workflows including visual design.
|
| 260 |
+
- **Full-Process Financial Research:** End-to-end investment research workflows.
|
| 261 |
+
- **Software Engineering:** Comprehensive coding tasks beyond traditional code generation, including front-end, visual development, and programmable hardware scenarios.
|
| 262 |
+
|
| 263 |
+
### Long-Horizon Agent Workflows
|
| 264 |
+
|
| 265 |
+
The model is specifically optimized for agent workflows that require:
|
| 266 |
+
|
| 267 |
+
- Searching and information retrieval
|
| 268 |
+
- Running code and processing tool returns
|
| 269 |
+
- Multi-turn tool calls with sustained execution
|
| 270 |
+
- Iterative refinement based on intermediate results
|
| 271 |
+
|
| 272 |
+
---
|
| 273 |
+
|
| 274 |
+
## ⚡ Quickstart
|
| 275 |
+
|
| 276 |
+
### Installation
|
| 277 |
+
|
| 278 |
+
```bash
|
| 279 |
+
pip install transformers>=4.56.0
|
| 280 |
+
pip install torch>=2.4.0
|
| 281 |
+
pip install accelerate
|
| 282 |
+
```
|
| 283 |
+
|
| 284 |
+
For video/image support:
|
| 285 |
+
|
| 286 |
+
```bash
|
| 287 |
+
pip install av pillow
|
| 288 |
+
```
|
| 289 |
+
|
| 290 |
+
### Basic Usage with Transformers
|
| 291 |
+
|
| 292 |
+
```python
|
| 293 |
+
from transformers import AutoModelForCausalLM, AutoTokenizer
|
| 294 |
+
|
| 295 |
+
model_id = "SHSLab/Step-5-Preview-BF16"
|
| 296 |
+
|
| 297 |
+
tokenizer = AutoTokenizer.from_pretrained(model_id, trust_remote_code=True)
|
| 298 |
+
model = AutoModelForCausalLM.from_pretrained(
|
| 299 |
+
model_id,
|
| 300 |
+
trust_remote_code=True,
|
| 301 |
+
device_map="auto",
|
| 302 |
+
torch_dtype="bfloat16",
|
| 303 |
+
)
|
| 304 |
+
|
| 305 |
+
messages = [
|
| 306 |
+
{"role": "system", "content": "You are a helpful assistant."},
|
| 307 |
+
{"role": "user", "content": "Explain the significance of the Pareto Frontier in AI scaling."},
|
| 308 |
+
]
|
| 309 |
+
|
| 310 |
+
inputs = tokenizer.apply_chat_template(
|
| 311 |
+
messages,
|
| 312 |
+
add_generation_prompt=True,
|
| 313 |
+
return_tensors="pt",
|
| 314 |
+
).to(model.device)
|
| 315 |
+
|
| 316 |
+
outputs = model.generate(
|
| 317 |
+
inputs,
|
| 318 |
+
max_new_tokens=1024,
|
| 319 |
+
temperature=0.7,
|
| 320 |
+
top_p=0.95,
|
| 321 |
+
reasoning_effort="high", # low / medium / high / xhigh
|
| 322 |
+
)
|
| 323 |
+
|
| 324 |
+
response = tokenizer.decode(outputs[0][inputs.shape[1]:], skip_special_tokens=True)
|
| 325 |
+
print(response)
|
| 326 |
+
```
|
| 327 |
+
|
| 328 |
+
### Multimodal (Image + Video) Usage
|
| 329 |
+
|
| 330 |
+
```python
|
| 331 |
+
from transformers import AutoProcessor
|
| 332 |
+
|
| 333 |
+
processor = AutoProcessor.from_pretrained(model_id, trust_remote_code=True)
|
| 334 |
+
|
| 335 |
+
messages = [
|
| 336 |
+
{
|
| 337 |
+
"role": "user",
|
| 338 |
+
"content": [
|
| 339 |
+
{"type": "image", "url": "https://example.com/image.jpg"},
|
| 340 |
+
{"type": "video", "url": "https://example.com/video.mp4"},
|
| 341 |
+
{"type": "text", "text": "Describe the scene and summarize the video."},
|
| 342 |
+
],
|
| 343 |
+
}
|
| 344 |
+
]
|
| 345 |
+
|
| 346 |
+
inputs = processor.apply_chat_template(messages, add_generation_prompt=True, return_tensors="pt")
|
| 347 |
+
# ... generate as above
|
| 348 |
+
```
|
| 349 |
+
|
| 350 |
+
### Tool Calling
|
| 351 |
+
|
| 352 |
+
```python
|
| 353 |
+
tools = [
|
| 354 |
+
{
|
| 355 |
+
"type": "function",
|
| 356 |
+
"function": {
|
| 357 |
+
"name": "get_weather",
|
| 358 |
+
"parameters": {
|
| 359 |
+
"type": "object",
|
| 360 |
+
"properties": {"city": {"type": "string"}},
|
| 361 |
+
"required": ["city"],
|
| 362 |
+
},
|
| 363 |
+
},
|
| 364 |
+
}
|
| 365 |
+
]
|
| 366 |
+
|
| 367 |
+
messages = [{"role": "user", "content": "What's the weather in Tokyo?"}]
|
| 368 |
+
|
| 369 |
+
inputs = tokenizer.apply_chat_template(
|
| 370 |
+
messages,
|
| 371 |
+
tools=tools,
|
| 372 |
+
add_generation_prompt=True,
|
| 373 |
+
return_tensors="pt",
|
| 374 |
+
).to(model.device)
|
| 375 |
+
|
| 376 |
+
outputs = model.generate(inputs, max_new_tokens=256, reasoning_effort="medium")
|
| 377 |
+
print(tokenizer.decode(outputs[0][inputs.shape[1]:], skip_special_tokens=True))
|
| 378 |
+
```
|
| 379 |
+
|
| 380 |
+
---
|
| 381 |
+
|
| 382 |
+
## 🚢 Deployment
|
| 383 |
+
|
| 384 |
+
### vLLM
|
| 385 |
+
|
| 386 |
+
```bash
|
| 387 |
+
vllm serve SHSLab/Step-5-Preview-BF16 \
|
| 388 |
+
--trust-remote-code \
|
| 389 |
+
--tensor-parallel-size 8 \
|
| 390 |
+
--max-model-len 1000000 \
|
| 391 |
+
--enable-reasoning \
|
| 392 |
+
--reasoning-parser stepfun
|
| 393 |
+
```
|
| 394 |
+
|
| 395 |
+
### SGLang
|
| 396 |
+
|
| 397 |
+
```bash
|
| 398 |
+
python -m sglang.launch_server \
|
| 399 |
+
--model-path SHSLab/Step-5-Preview-BF16 \
|
| 400 |
+
--trust-remote-code \
|
| 401 |
+
--tp 8 \
|
| 402 |
+
--context-length 1000000 \
|
| 403 |
+
--reasoning-parser stepfun
|
| 404 |
+
```
|
| 405 |
+
|
| 406 |
+
### OpenAI-Compatible API
|
| 407 |
+
|
| 408 |
+
```python
|
| 409 |
+
from openai import OpenAI
|
| 410 |
+
|
| 411 |
+
client = OpenAI(
|
| 412 |
+
api_key="YOUR_STEP_API_KEY",
|
| 413 |
+
base_url="https://api.stepfun.com/v1",
|
| 414 |
+
)
|
| 415 |
+
|
| 416 |
+
response = client.chat.completions.create(
|
| 417 |
+
model="step-5-preview",
|
| 418 |
+
messages=[{"role": "user", "content": "Write a Python function to merge two sorted lists."}],
|
| 419 |
+
reasoning_effort="high",
|
| 420 |
+
max_tokens=2048,
|
| 421 |
+
)
|
| 422 |
+
|
| 423 |
+
print(response.choices[0].message.content)
|
| 424 |
+
```
|
| 425 |
+
|
| 426 |
+
<div style="background-color: #f9f0ff; padding: 16px; border-radius: 8px; border-left: 6px solid #722ed1; margin: 20px 0;">
|
| 427 |
+
<strong>📦 Recommended Deployment Configurations</strong><br>
|
| 428 |
+
• <strong>BF16:</strong> 8× H100 80GB (tensor parallel)<br>
|
| 429 |
+
• <strong>FP8:</strong> 4× H100 80GB (coming soon)<br>
|
| 430 |
+
• <strong>Context length:</strong> Up to 1M tokens<br>
|
| 431 |
+
• <strong>Reasoning parser:</strong> Use <code>stepfun</code> for vLLM/SGLang
|
| 432 |
+
</div>
|
| 433 |
+
|
| 434 |
+
---
|
| 435 |
+
|
| 436 |
+
## 📈 Evaluation
|
| 437 |
+
|
| 438 |
+
Step-5-Preview was evaluated on a comprehensive suite of public and internal benchmarks.
|
| 439 |
+
All evaluations used the model's `high` reasoning effort setting unless otherwise noted.
|
| 440 |
+
|
| 441 |
+
| Benchmark | Score | Notes |
|
| 442 |
+
|:---|:---|:---|
|
| 443 |
+
| **DeepSWE v1.1** | 67.7 | SWE-agent harness, temp=1.0, top_p=0.95 |
|
| 444 |
+
| **StepCodeBench** | 49.0 | avg@4 |
|
| 445 |
+
| **ProgramBench** | 80.5 | — |
|
| 446 |
+
| **Terminal-Bench v4** | 33.3 | — |
|
| 447 |
+
| **Agents' Last Exam (ALE-CLI)** | 29.5 | — |
|
| 448 |
+
| **GDPval-AA v2** | 1571 | Artificial Analysis, Sep 19, 2026 |
|
| 449 |
+
| **FrontierFinance** | 66.4 | — |
|
| 450 |
+
| **DRACO** | 83.3 | — |
|
| 451 |
+
| **SciCode** | Higher than Kimi K3 | — |
|
| 452 |
+
| **Output Speed** | 99.8 tokens/sec | GLM-5.3: 72.1 tokens/sec |
|
| 453 |
+
| **Time to First Token** | 2.96s | GLM-5.3: 2.99s; Claude Opus 5: 56.84s (max effort) |
|
| 454 |
+
|
| 455 |
+
---
|
| 456 |
+
|
| 457 |
+
## 📚 Citation
|
| 458 |
+
|
| 459 |
+
If you use Step-5-Preview in your research, please cite:
|
| 460 |
+
|
| 461 |
+
```bibtex
|
| 462 |
+
@misc{stepfun2026step5preview,
|
| 463 |
+
title = {Step-5-Preview: A 600B Sparse MoE Foundation Model for Real-World Agentic Work},
|
| 464 |
+
author = {StepFun Team},
|
| 465 |
+
year = {2026},
|
| 466 |
+
howpublished = {\url{https://huggingface.co/SHSLab/Step-5-Preview-BF16}},
|
| 467 |
+
note = {Released September 20, 2026}
|
| 468 |
+
}
|
| 469 |
+
```
|
| 470 |
+
|
| 471 |
+
---
|
| 472 |
+
|
| 473 |
+
## 📜 License
|
| 474 |
+
|
| 475 |
+
Step-5-Preview is released under the **StepFun Community License**.
|
| 476 |
+
See the [LICENSE](https://huggingface.co/SHSLab/Step-5-Preview-BF16/blob/main/LICENSE) file for full terms.
|
| 477 |
+
|
| 478 |
+
<div style="background-color: #fffbe6; padding: 16px; border-radius: 8px; border-left: 6px solid #faad14; margin: 20px 0;">
|
| 479 |
+
<strong>⚠️ Usage Restrictions</strong><br>
|
| 480 |
+
• Commercial use is permitted under the StepFun Community License.<br>
|
| 481 |
+
• Redistribution must include the license and attribution.<br>
|
| 482 |
+
• See LICENSE for full details.
|
| 483 |
+
</div>
|
| 484 |
+
|
| 485 |
+
---
|
| 486 |
+
|
| 487 |
+
## 📬 Contact
|
| 488 |
+
|
| 489 |
+
- **Hugging Face:** [SHSLab](https://huggingface.co/SHSLab)
|
| 490 |
+
- **GitHub:** [github.com/stepfun-ai](https://github.com/stepfun-ai)
|
| 491 |
+
- **Discord:** [Join our Discord](https://discord.gg/stepfun)
|
| 492 |
+
- **Email:** [opensource@stepfun.com](mailto:opensource@stepfun.com)
|
| 493 |
+
- **Website:** [stepfun.com](https://stepfun.com)
|
| 494 |
+
|
| 495 |
+
---
|
| 496 |
+
|
| 497 |
+
<div align="center">
|
| 498 |
+
<strong>⭐ If you find Step-5-Preview useful, please give us a star on GitHub and Hugging Face! ⭐</strong>
|
| 499 |
+
<br><br>
|
| 500 |
+
<em>Built with ❤️ by StepFun</em>
|
| 501 |
+
</div>
|