Step 5 Preview

stepfun-ai/step-5-preview

Preview of StepFun's Step 5: ~600B-total / 27B-active multimodal MoE (text and image in, text out) with 1M context, reasoning and tool calling, served in NVFP4.

Context Length

1,048,576 tokens

Input Pricing

Not published

Output Pricing

Not published

Recent Latency

No probes

Model Architecture & Limits

Canonical IDstepfun-ai/step-5-preview

Publisher / Originatorstepfun-ai

Model FamilyStep

ArchitectureTransformer (Mixture-of-Experts)

Context Window Limit1,048,576 tokens

Max Output Tokens4,096 tokens

Endpoint Protocolopenai-chat

Capabilities & Modal Surfaces

Chat Conversation✓ Yes

Tool / Function Calling✓ Yes

Reasoning / Thinking✕ No

Structured Output (JSON)✓ Yes

Vision / Multimodal✓ Yes

Audio Processing✕ No

License & Restrictions

**GOVERNING TERMS:** The trial service is governed by the [NVIDIA API Trial Terms of Service](https://assets.ngc.nvidia.com/products/api-catalog/legal/NVIDIA%20API%20Trial%20Terms%20of%20Service.pdf); and the use of this model is governed by the [NVIDIA Open Model Agreement](https://www.nvidia.com/e

Commercial and research use permitted under governing model and API terms.