GPT-5.3-Codex-Spark vs StepFun Step-2
GPT-5.3-Codex-Spark (2026) and StepFun Step-2 (2025) compare a coding-specialized model against a standalone API model. GPT-5.3-Codex-Spark ships a 131k-token context window, while StepFun Step-2 ships a 128k-token context window. This page treats the result as workflow and deployment fit, not a universal model winner.
Treat this as a product-type comparison: GPT-5.3-Codex-Spark is coding-specialized model, while StepFun Step-2 is standalone API model. Choose based on workflow fit before reading any benchmark or price row as decisive.
Decision scorecard
Local evidence first| Signal | GPT-5.3-Codex-Spark | StepFun Step-2 |
|---|---|---|
| Product type | Coding-specialized model | Standalone API model |
| Best for | custom coding agents, code generation, and tool loops | general production evaluation |
| Decision fit | Coding, RAG, and Agents | Long context |
| Context window | 131k | 128k |
| Cheapest output | - | - |
| Provider routes | 1 tracked | 0 tracked |
| Shared benchmarks | 0 shared | 0 shared |
Decision tradeoffs
- GPT-5.3-Codex-Spark has the larger context window for long prompts, retrieval packs, or transcript analysis.
- GPT-5.3-Codex-Spark has broader tracked provider coverage for fallback and route flexibility.
- GPT-5.3-Codex-Spark uniquely exposes JSON / Tool use, Structured outputs, and Code execution in local model data.
- Local decision data tags GPT-5.3-Codex-Spark 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-5.3-Codex-Spark
Unavailable
No complete token price in local provider data
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-5.3-Codex-Spark and StepFun Step-2; plan for SDK, billing, or endpoint changes.
- Check replacement coverage for JSON / Tool use, Structured outputs, and Code execution before moving production traffic.
- No overlapping tracked provider route is sourced for StepFun Step-2 and GPT-5.3-Codex-Spark; plan for SDK, billing, or endpoint changes.
- GPT-5.3-Codex-Spark adds JSON / Tool use, Structured outputs, and Code execution in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-02-12 | 2025-10-15 |
| Context window | 131k | 128k |
| Parameters | — | 1T (MoE)* |
| Architecture | Decoder Only | - |
| License | Proprietary | Proprietary |
| Openness | Proprietary | Proprietary |
| Weights | Not released | Not released |
| Code | Unknown | Unknown |
| Commercial use | Commercial use: conditional | Commercial use: conditional |
| Knowledge cutoff | - | - |
Pricing and availability
| Pricing attribute | GPT-5.3-Codex-Spark | StepFun Step-2 |
|---|---|---|
| Input price | - | - |
| Output price | - | - |
| Providers | - |
Pricing not yet sourced for either model.
Capabilities
| Capability | GPT-5.3-Codex-Spark | StepFun Step-2 |
|---|---|---|
| Vision | No | No |
| Multimodal | No | No |
| Reasoning | No | No |
| JSON / 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 scores are currently available for this pair.
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Last reviewed: 2026-06-29. Data sourced from public model cards and provider documentation.