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Compare performance benchmarks, coding intelligence, reasoning evaluations, context limits, and API economics between Step 5 Preview (StepFun) and Claude Haiku 5.5 (Anthropic).
| Metric / Capability | Step 5 Preview | Claude Haiku 5.5 |
|---|---|---|
| Developer / Organization | StepFun | Anthropic |
| Release Date | 2026-10-08 | 2026-10-07 |
| Deployment / Weights | Open Weights | Proprietary Cloud API |
| Context Window | 1.0M tokens (1,048,576 tokens) | 1M tokens (1,000,000 tokens) |
| Input Pricing (/1M Tokens) | Free (Open Weights) | $0.1 |
| Output Pricing (/1M Tokens) | Free (Open Weights) | $0.5 |
| Benchmark / Domain | Step 5 Preview | Claude Haiku 5.5 | Advantage |
|---|---|---|---|
Artificial Analysis Intelligence Index Composite index aggregating 10+ evaluations of general reasoning and knowledge. | 43.7% | 43.4% | Step 5 Preview (+1%) |
Artificial Analysis Coding Agent Index v2.0 Composite index of coding-agent systems (model + harness) across FrontierCode v1.1, SWE-Atlas-QnA, and Terminal-Bench v4. | 43.1% | 37.3% | Step 5 Preview (+16%) |
Terminal-Bench 4.0 Sandboxed command-line tasks requiring shell and file-system operation. | 33.3% | 39.2% | Claude Haiku 5.5 (+18%) |
ARC-AGI-2 Novel visual grid puzzles requiring abstract rule induction. | — | 61.3% | — |
GPQA Diamond Graduate-level physics, chemistry, and biology questions written by domain experts. | 93.5% | — | — |
Humanity's Last Exam Expert-written questions across hundreds of disciplines designed to resist saturation. | 46.5% | 45.9% | Step 5 Preview (+1%) |
FrontierMath v2 (Tiers 1-3) Unpublished, research-level mathematics problems across Tiers 1-3. | — | 75.1% | — |
Design Arena ELO Human-preference ELO across UI, 3D, data-visualization, and game-dev generations. | — | 1344 | — |
Step 5 Preview leads across 3 evaluated benchmarks compared to 1 for Claude Haiku 5.5, showing notable advantages in Artificial Analysis Intelligence Index, Artificial Analysis Coding Agent Index v2.0, Humanity's Last Exam.
Step 5 Preview offers a larger context capacity of 1.0M tokens (1,048,576 tokens), compared to 1M tokens for Claude Haiku 5.5.
Step 5 Preview is more cost-effective. Input tokens cost $Free (Open Weights)/M tokens vs $0.1/M tokens for Claude Haiku 5.5.
Step 5 Preview is an open-weights model. Claude Haiku 5.5 is a proprietary cloud API.
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