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README.md
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@@ -511,169 +511,4 @@ As we work to shape the future of AGI by expanding broad model capabilities, we
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- **Report Friction**: Encountering limitations? You can open an issue on GitHub or flag it directly in our Discord support channels.
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## License
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This project is open-sourced under the [Apache 2.0 License](https://www.apache.org/licenses/LICENSE-2.0).
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## 1. Introduction
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**Step3.5** is our most capable open-source reasoning model, purpose-built for agentic workflows.
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It bridges the gap between massive scale and high performance by combining 196B parameters of knowledge with the inference latency of an 11B model.
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We prioritized developer needs to balance speed, cost, and accessibility. This enables the creation of production-grade agents that are fast, stable, and cost-effective.
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## 2. Key Capabilities
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- Frontier intelligence at 200 tokens/s: Step3.5 matches GPT-5 and Gemini 3.0 Pro in reasoning but runs 4x faster. By leveraging Multi-Token Prediction (MTP-3), Step3.5 predicts three tokens simultaneously, achieving 200 tokens/s for real-time responsiveness.
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- Easy local deployment: Despite its massive 196B total parameter count, Step3.5's sparse MoE architecture allows it to run locally on high-end consumer hardware (e.g. Mac Studio M2/M3 Ultra). This enables secure, offline deployment of elite-level intelligence.
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- Agentic & coding mastery: Step3.5 is fine-tuned for reliability. It achieves 85.5% on LiveCodeBench and 72.1% on SWE-bench Verified, making it a robust engine for autonomous software engineering and multi-step planning.
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- Cost-effective long context: Optimized with a 3:1 sliding window attention strategy (512 window), Step3.5 handles extended contexts with minimal memory overhead, perfect for RAG applications and analyzing large codebases.
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## 3. Benchmarks
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## Architecture
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### Key Features:
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- Hybrid Attention Schedules and Compensation for SWA
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- Mixture-of-Experts Routing And Load balancing
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### Architecture Details
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- Backbone: 45-layer Transformer
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- Vocabulary: 128,896 tokens
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- Hidden Dim: 4,096
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- MoE Blocks:
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- 288 routed experts + 1 shared expert per block
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- Top-8 expert selection per token
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- Parameters: Total:
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196.81B (Backbone: 196B + MTP Head: 0.81B)
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- Activated per token:
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11B (excludes embedding/output projections)
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- Special Components:
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Multi-token Prediction (MTP) head with sliding-window attention and dense FFN
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## 5. Getting started
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## Deployment Resource Specifications
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- Model Weights: 20 GB
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- Runtime Overhead: ~4 GB
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- Minimum VRAM Required: 24 GB (e.g., RTX 4090 or A100)
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## Deploy Step3.5 Locally
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For local deployment, Step3.5-preview supports inference frameworks including vLLM and SGLang. Comprehensive deployment instructions are available in the official [Github](#) repository.
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vLLM and SGLang only support Step3.5-preview on their main branches. you can use their official docker images for inference.
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### vLLM
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Using Docker as:
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```shell
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docker pull vllm/vllm-openai:nightly
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```
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or using pip (must use pypi.org as the index url):
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```shell
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pip install -U vllm --pre --index-url https://pypi.org/simple --extra-index-url https://wheels.vllm.ai/nightly
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```
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### SGLang
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Using Docker as:
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```shell
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docker pull lmsysorg/sglang:dev
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```
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or using pip install sglang from source.
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### transformers
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```python
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import torch
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from transformers import AutoModelForCausalLM, AutoTokenizer
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MODEL_PATH = "xxxxxx"
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messages = [{"role": "user", "content": "hello"}]
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tokenizer = AutoTokenizer.from_pretrained(MODEL_PATH)
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inputs = tokenizer.apply_chat_template(
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messages,
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tokenize=True,
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add_generation_prompt=True,
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return_dict=True,
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return_tensors="pt",
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)
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model = AutoModelForCausalLM.from_pretrained(
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pretrained_model_name_or_path=MODEL_PATH,
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torch_dtype=torch.bfloat16,
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device_map="auto",
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)
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inputs = inputs.to(model.device)
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generated_ids = model.generate(**inputs, max_new_tokens=128, do_sample=False)
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output_text = tokenizer.decode(generated_ids[0][inputs.input_ids.shape[1] :])
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print(output_text)
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```
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### vLLM
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```shell
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vllm serve {xxx} \
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--tensor-parallel-size 4 \
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--speculative-config.method mtp \
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--speculative-config.num_speculative_tokens 1 \
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--tool-call-parser {xxx} \
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--reasoning-parser {xxx} \
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--enable-auto-tool-choice \
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--served-model-name {xxx}
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```
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### SGLang
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```shell
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python3 -m sglang.launch_server \
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--model-path {xxx} \
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--tp-size 8 \
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--tool-call-parser {xxx} \
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--reasoning-parser {xxx} \
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--speculative-algorithm EAGLE \
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--speculative-num-steps 3 \
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--speculative-eagle-topk 1 \
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--speculative-num-draft-tokens 4 \
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--mem-fraction-static 0.8 \
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--served-model-name {xxx} \
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--host 0.0.0.0 \
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--port 8000
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```
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### Parameter Instructions
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- When using `vLLM` and `SGLang`, thinking mode is enabled by default when sending requests.
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- Both support tool calling. Please use OpenAI-style tool description format for calls.
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<!-- ## Citation
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If you find our work useful in your research, please consider citing the following paper:
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```bibtex
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@misc{xxxx,
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title={Step3.5-preview},
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author={StepFun Team},
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year={2026},
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eprint={xxxx},
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archivePrefix={arXiv},
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primaryClass={cs.CL},
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url={https://arxiv.org/abs/xxxxx},
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}
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``` -->
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## 📄 License
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This project is open-sourced under the [Apache 2.0 License](https://www.google.com/search?q=LICENSE).
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- **Report Friction**: Encountering limitations? You can open an issue on GitHub or flag it directly in our Discord support channels.
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## License
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This project is open-sourced under the [Apache 2.0 License](https://www.apache.org/licenses/LICENSE-2.0).
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