GPT-5.4 vs StepFun Step-2
GPT-5.4 (2026) and StepFun Step-2 (2025) are frontier reasoning models from OpenAI and StepFun. GPT-5.4 ships a 1.05m-token context window, while StepFun Step-2 ships a 128k-token context window. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads. It focuses on practical selection signals rather than broad model-family marketing.
GPT-5.4 fits 8x more tokens; pick it for long-context work and StepFun Step-2 for tighter calls.
Decision scorecard
Local evidence first| Signal | GPT-5.4 | StepFun Step-2 |
|---|---|---|
| Best for | reasoning-heavy apps, multimodal apps, and tool-calling agents | general production evaluation |
| Decision fit | Coding, RAG, and Agents | Long context |
| Context window | 1.05m | 128k |
| Cheapest output | $15/1M tokens | - |
| Provider routes | 3 tracked | 0 tracked |
| Shared benchmarks | 0 rows | 0 rows |
Decision tradeoffs
- GPT-5.4 has the larger context window for long prompts, retrieval packs, or transcript analysis.
- GPT-5.4 has broader tracked provider coverage for fallback and procurement flexibility.
- GPT-5.4 uniquely exposes Vision, Multimodal, and Reasoning in local model data.
- Local decision data tags GPT-5.4 for Coding, RAG, and Agents.
- Local decision data tags StepFun Step-2 for Long context.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output route or tier on this page.
GPT-5.4
$5,750
Cheapest tracked route/tier: OpenAI API
StepFun Step-2
Unavailable
No complete token price in local provider data
Cost delta unavailable until both models have sourced input and output token prices.
Switch friction
- No overlapping tracked provider route is sourced for GPT-5.4 and StepFun Step-2; plan for SDK, billing, or endpoint changes.
- Check replacement coverage for Vision, Multimodal, and Reasoning before moving production traffic.
- No overlapping tracked provider route is sourced for StepFun Step-2 and GPT-5.4; plan for SDK, billing, or endpoint changes.
- GPT-5.4 adds Vision, Multimodal, and Reasoning in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-03-05 | 2025-10-15 |
| Context window | 1.05m | 128k |
| Parameters | — | 1T (MoE)* |
| Architecture | decoder only | - |
| License | Proprietary | Proprietary |
| Openness | Proprietary | Proprietary |
| Commercial use | Commercial use with conditions | Commercial use with conditions |
| Knowledge cutoff | 2025-08 | - |
Pricing and availability
| Pricing attribute | GPT-5.4 | StepFun Step-2 |
|---|---|---|
| Input price |
| - |
| Output price |
| - |
| Providers | - |
Capabilities
| Capability | GPT-5.4 | StepFun Step-2 |
|---|---|---|
| Vision | Yes | No |
| Multimodal | Yes | No |
| Reasoning | Yes | No |
| Function calling | Yes | No |
| Tool use | Yes | No |
| Structured outputs | Yes | No |
| Code execution | Yes | No |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
No shared benchmark rows are currently sourced for this pair.
Deep dive
The capability footprint differs most on vision: GPT-5.4, multimodal input: GPT-5.4, reasoning mode: GPT-5.4, function calling: GPT-5.4, tool use: GPT-5.4, structured outputs: GPT-5.4, and code execution: GPT-5.4. 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: GPT-5.4 has $2.50/1M input tokens and StepFun Step-2 has no token price sourced yet. Provider availability is 3 tracked routes versus 0. Treat unknown pricing as an integration gap, then verify the route you will actually call before estimating production spend.
Choose GPT-5.4 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. It also helps separate model capability from provider packaging, which can change cost and latency.
FAQ
Which has a larger context window, GPT-5.4 or StepFun Step-2?
GPT-5.4 supports 1.05m 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. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Is GPT-5.4 or StepFun Step-2 open source?
GPT-5.4 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, GPT-5.4 or StepFun Step-2?
GPT-5.4 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. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Which is better for multimodal input, GPT-5.4 or StepFun Step-2?
GPT-5.4 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, GPT-5.4 or StepFun Step-2?
GPT-5.4 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 GPT-5.4 and StepFun Step-2?
GPT-5.4 is available on OpenAI API, OpenRouter, and Vercel AI Gateway. StepFun Step-2 is available on the tracked providers still being sourced. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
Continue comparing
Last reviewed: 2026-06-04. Data sourced from public model cards and provider documentation.