GPT-5.4-Cyber vs Step 3.5 Flash
GPT-5.4-Cyber (2026) and Step 3.5 Flash (2026) are frontier-tier reasoning models from OpenAI and StepFun. GPT-5.4-Cyber ships a not-yet-sourced context window, while Step 3.5 Flash ships a 256k-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-Cyber is safer overall; choose Step 3.5 Flash when provider fit matters.
Decision scorecard
Local evidence first| Signal | GPT-5.4-Cyber | Step 3.5 Flash |
|---|---|---|
| Best for | reasoning-heavy apps and multimodal apps | reasoning-heavy apps |
| Decision fit | Vision | Coding, Agents, and Long context |
| Context window | — | 256k |
| Cheapest output | - | $0.30/1M tokens |
| Provider routes | 0 tracked | 1 tracked |
| Shared benchmarks | 0 shared | 0 shared |
Decision tradeoffs
- GPT-5.4-Cyber uniquely exposes Vision and Multimodal in local model data.
- Local decision data tags GPT-5.4-Cyber for Vision.
- Step 3.5 Flash has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Step 3.5 Flash has broader tracked provider coverage for fallback and route flexibility.
- Local decision data tags Step 3.5 Flash for Coding, Agents, and 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-Cyber
Unavailable
No complete token price in local provider data
Step 3.5 Flash
$155
Cheapest tracked route/tier: OpenRouter
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-Cyber and Step 3.5 Flash; plan for SDK, billing, or endpoint changes.
- Check replacement coverage for Vision and Multimodal before moving production traffic.
- No overlapping tracked provider route is sourced for Step 3.5 Flash and GPT-5.4-Cyber; plan for SDK, billing, or endpoint changes.
- GPT-5.4-Cyber adds Vision and Multimodal in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-04-14 | 2026-01-29 |
| Context window | — | 256k |
| Parameters | — | 196B (11B active) |
| Architecture | Decoder Only | Mixture of Experts |
| License | Proprietary | Proprietary |
| Openness | Proprietary | Proprietary |
| Weights | Not released | Not released |
| Code | Unknown | Unknown |
| Commercial use | Commercial use: conditional | Commercial use: conditional |
| Knowledge cutoff | 2025-08 | - |
Pricing and availability
| Pricing attribute | GPT-5.4-Cyber | Step 3.5 Flash |
|---|---|---|
| Input price | - | $0.10/1M tokens |
| Output price | - | $0.30/1M tokens |
| Providers | - |
Capabilities
| Capability | GPT-5.4-Cyber | Step 3.5 Flash |
|---|---|---|
| Vision | Yes | No |
| Multimodal | Yes | No |
| Reasoning | Yes | Yes |
| JSON / Tool use | No | No |
| Structured outputs | No | No |
| Code execution | No | No |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
No shared benchmark scores are currently available for this pair.
Continue comparing
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Last reviewed: 2026-06-29. Data sourced from public model cards and provider documentation.