Step 5 Preview
StepFun's 600B open-weight multimodal MoE, scoring 44 on the Artificial Analysis index
Context window
1M
Input / 1M tokens
$1.00
Output / 1M tokens
$2.70
Provider
StepFun
API launched September 20, 2026; open weights (BF16, FP8, NVFP4) released October 15 under the StepFun Model License 1.0 (Apache-style with commercial thresholds). Price shown is OpenRouter. · Data verified 2026-10-17
Step 5 Preview is StepFun's 600B-parameter Mixture-of-Experts model with 27B active per token, a 1M-token context and text, image and video input. Its API launched in September 2026 and open weights followed on October 15. Artificial Analysis scores it 44, the highest of this month's open-weight releases.
Capability index
Relative estimates (0-100) to place this model against its peers, grounded in published benchmarks.
How to access it
StepFun API, OpenRouter, or open weights on Hugging Face.
Strengths
- ✓Highest Artificial Analysis score among October 2026 open releases (44)
- ✓Open weights in BF16, FP8 and NVFP4
- ✓1M-token context
Best for developers who...
Benchmarks
| Benchmark | Score | Notes |
|---|---|---|
| Artificial Analysis Intelligence Index | 44 | Third-party |
| GPQA Diamond | 93.5 | StepFun-reported |
| DeepSWE v1.1 | 67.7 | StepFun-reported |
Source: Artificial Analysis
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