Claude Opus 4.5 vs StepFun Step-2
Claude Opus 4.5 (2025) and StepFun Step-2 (2025) are frontier reasoning models from Anthropic and StepFun. Claude Opus 4.5 ships a 200K-token context window, while StepFun Step-2 ships a 128k-token context window. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit. It focuses on practical selection signals rather than broad model-family marketing. The goal is to make the tradeoff clear before deeper testing.
Claude Opus 4.5 is safer overall; choose StepFun Step-2 when provider fit matters.
Specs
| Released | 2025-11-01 | 2025-10-15 |
| Context window | 200K | 128k |
| Parameters | — | — |
| Architecture | decoder only | - |
| License | Proprietary | Proprietary |
| Knowledge cutoff | 2025-12 | - |
Pricing and availability
| Claude Opus 4.5 | StepFun Step-2 | |
|---|---|---|
| Input price | $5/1M tokens | - |
| Output price | $25/1M tokens | - |
| Providers | - |
Capabilities
| Claude Opus 4.5 | StepFun Step-2 | |
|---|---|---|
| Vision | ||
| Multimodal | ||
| Reasoning | ||
| Function calling | ||
| Tool use | ||
| Structured outputs | ||
| Code execution |
Benchmarks
No shared benchmark rows are currently sourced for this pair.
Deep dive
The capability footprint differs most on vision: Claude Opus 4.5, multimodal input: Claude Opus 4.5, reasoning mode: Claude Opus 4.5, function calling: Claude Opus 4.5, tool use: Claude Opus 4.5, structured outputs: Claude Opus 4.5, and code execution: Claude Opus 4.5. Both models share the core language-model surface, so the practical split is not just feature count. Use those differences to decide whether the page is about raw model quality, agentic coding support, multimodal ingestion, or predictable structured API behavior.
Pricing coverage is uneven: Claude Opus 4.5 has $5/1M input tokens and StepFun Step-2 has no token price sourced yet. Provider availability is 6 tracked routes versus 0. Treat unknown pricing as an integration gap, then verify the route you will actually call before estimating production spend.
Choose Claude Opus 4.5 when coding workflow support, larger context windows, and broader provider choice are central to the workload. Choose StepFun Step-2 when provider fit are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship. This keeps the decision grounded in measurable tradeoffs instead of brand-level assumptions.
FAQ
Which has a larger context window, Claude Opus 4.5 or StepFun Step-2?
Claude Opus 4.5 supports 200K tokens, while StepFun Step-2 supports 128k tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Is Claude Opus 4.5 or StepFun Step-2 open source?
Claude Opus 4.5 is listed under Proprietary. StepFun Step-2 is listed under Proprietary. License labels affect whether you can self-host, redistribute weights, or rely only on hosted APIs, so confirm the upstream license before deployment.
Which is better for vision, Claude Opus 4.5 or StepFun Step-2?
Claude Opus 4.5 has the clearer documented vision signal in this comparison. If vision is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Which is better for multimodal input, Claude Opus 4.5 or StepFun Step-2?
Claude Opus 4.5 has the clearer documented multimodal input signal in this comparison. If multimodal input is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Which is better for reasoning mode, Claude Opus 4.5 or StepFun Step-2?
Claude Opus 4.5 has the clearer documented reasoning mode signal in this comparison. If reasoning mode is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Where can I run Claude Opus 4.5 and StepFun Step-2?
Claude Opus 4.5 is available on Microsoft Foundry, Anthropic, GCP Vertex AI, AWS Bedrock, and OpenRouter. StepFun Step-2 is available on the tracked providers still being sourced. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
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Last reviewed: 2026-04-24. Data sourced from public model cards and provider documentation.