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| 2 models | stepfun-aiStep-5-PreviewRemove × | stepfunStepFun: Step 3.5 FlashRemove × |
|---|---|---|
| What’s different | 600B total and 27B active parameters; accepts images and video, with FP8 and BF16 weights for deployment. | Step 3.5 Flash is StepFun's most capable open-source foundation model. Built on a sparse Mixture of Experts (MoE) architecture, it selectively activates only 11B of its 196B parameters per token.... |
| Date | Sep 18, 2026Released | Jan 29, 2026Listed |
API prices USD · provider configuration shown below | ||
| Listed rate | $1.00 in / $2.70 out/ 1M tokensDeepInfra · all routes ↗ | $0.10 in / $0.30 out/ 1M tokensdeepinfra · via Hugging Face · all routes ↗ |
| Provider endpoints | 6 endpoints → | 4 endpoints → |
Benchmarks Each result retains its evaluation configuration | ||
| AA Intelligence ↗4.3.2 | 43.73 ↗Effort not specifiedIndependent result | Not reported |
| AA-Briefcase ↗1.1 | 1,424.32 ↗Effort not specifiedIndependent result | Not reported |
| GDPval-AA ↗2.1 | 1,586.63 ↗Effort not specifiedIndependent result | Not reported |
| AutomationBench-AA ↗AA Index 4.3.2 collection | 50.96% ↗Effort not specifiedIndependent result | Not reported |
| Terminal-Bench 4.0 · AA ↗ | 33.33% ↗Effort not specifiedHarness unreportedIndependent result | Not reported |
| SciCode ↗AA Index 4.3.2 collection | 58.91% ↗AA · Under reviewEffort not specifiedIndependent result | Not reported |
| Humanity’s Last Exam ↗AA Index 4.3.2 collection | 46.48% ↗Effort not specifiedIndependent result | Not reported |
| GDP.pdf ↗AA Index 4.3.2 collection | 14.8% ↗Effort not specifiedIndependent result | Not reported |
| CritPt ↗AA Index 4.3.2 collection | 20.86% ↗AA · Under reviewEffort not specifiedIndependent result | Not reported |
| AA-Omniscience ↗AA Index 4.3.2 collection | 16.38 ↗Effort not specifiedIndependent result | Not reported |
| AA-LCR ↗1.1 | 88.33% ↗Effort not specifiedIndependent result | Not reported |
| LiveBench ↗2.0 · 2026-10-14 (dataset 2026-09-02) | 62.01% ↗Effort: max · single run · equal mean of 7 suitesIndependent result | Not reported |
| LiveBench Design ↗2.0 · 2026-10-14 (dataset 2026-09-02) | 76.9% ↗Effort: max · single runIndependent result | Not reported |
| LiveBench Research ↗2.0 · 2026-10-14 (dataset 2026-09-02) | 72.8% ↗Effort: max · single runIndependent result | Not reported |
| LiveBench Browser Use ↗2.0 · 2026-10-14 (dataset 2026-09-02) | 24% ↗Effort: max · single runIndependent result | Not reported |
| LiveBench Coding ↗2.0 · 2026-10-14 (dataset 2026-09-02) | 85.6% ↗Effort: max · single runIndependent result | Not reported |
| LiveBench Agentic ↗2.0 · 2026-10-14 (dataset 2026-09-02) | 27.5% ↗Effort: max · single runIndependent result | Not reported |
| LiveBench Data Analysis ↗2.0 · 2026-10-14 (dataset 2026-09-02) | 63.5% ↗Effort: max · single runIndependent result | Not reported |
| LiveBench Reasoning ↗2.0 · 2026-10-14 (dataset 2026-09-02) | 83.8% ↗Effort: max · single runIndependent result | Not reported |
Specifications | ||
| Context window | 1M | 262.1K |
| Max output | 64K | 65.5K |
| Parameters | — | — |
| Tool calling | Supported | Supported |
| Structured output | Supported | Supported |
| Image input | Supported | Not reported |
| Video input | Supported | Not reported |
| Reasoning | Supported | Supported |
| Prompt caching | Supported | Not reported |
| Open weights | Supported | Supported |