GPT-5.3-Codex-Spark vs Phi-4 Reasoning Vision 15B
GPT-5.3-Codex-Spark (2026) and Phi-4 Reasoning Vision 15B (2026) compare a coding-specialized model against a standalone API model. GPT-5.3-Codex-Spark ships a 131k-token context window, while Phi-4 Reasoning Vision 15B ships a not-yet-sourced 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 Phi-4 Reasoning Vision 15B 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 | Phi-4 Reasoning Vision 15B |
|---|---|---|
| Product type | Coding-specialized model | Standalone API model |
| Best for | custom coding agents, code generation, and tool loops | multimodal apps |
| Decision fit | Coding, RAG, and Agents | Vision |
| Context window | 131k | — |
| 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 procurement flexibility.
- GPT-5.3-Codex-Spark uniquely exposes Function calling, Tool use, and Structured outputs in local model data.
- Local decision data tags GPT-5.3-Codex-Spark for Coding, RAG, and Agents.
- Phi-4 Reasoning Vision 15B uniquely exposes Vision and Multimodal in local model data.
- Local decision data tags Phi-4 Reasoning Vision 15B for Vision.
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
Phi-4 Reasoning Vision 15B
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 Phi-4 Reasoning Vision 15B; plan for SDK, billing, or endpoint changes.
- Check replacement coverage for Function calling, Tool use, and Structured outputs before moving production traffic.
- Phi-4 Reasoning Vision 15B adds Vision and Multimodal in local capability data.
- No overlapping tracked provider route is sourced for Phi-4 Reasoning Vision 15B and GPT-5.3-Codex-Spark; plan for SDK, billing, or endpoint changes.
- Check replacement coverage for Vision and Multimodal before moving production traffic.
- GPT-5.3-Codex-Spark adds Function calling, Tool use, and Structured outputs in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-02-12 | 2026-03-12 |
| Context window | 131k | — |
| Parameters | — | 15B |
| Architecture | Decoder Only | - |
| License | Proprietary | MITOSI-approved |
| Openness | Proprietary | Open source |
| Commercial use | Commercial use: conditional | Commercial use: permitted |
| Knowledge cutoff | - | 2025-03 |
Pricing and availability
| Pricing attribute | GPT-5.3-Codex-Spark | Phi-4 Reasoning Vision 15B |
|---|---|---|
| Input price | - | - |
| Output price | - | - |
| Providers | - |
Pricing not yet sourced for either model.
Capabilities
| Capability | GPT-5.3-Codex-Spark | Phi-4 Reasoning Vision 15B |
|---|---|---|
| Vision | No | Yes |
| Multimodal | No | Yes |
| Reasoning | No | 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 scores are currently available for this pair.
Deep dive
The capability footprint differs most on vision: Phi-4 Reasoning Vision 15B, multimodal input: Phi-4 Reasoning Vision 15B, function calling: GPT-5.3-Codex-Spark, tool use: GPT-5.3-Codex-Spark, structured outputs: GPT-5.3-Codex-Spark, and code execution: GPT-5.3-Codex-Spark. 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-5.3-Codex-Spark has no token price sourced yet and Phi-4 Reasoning Vision 15B has no token price sourced yet. Provider availability is 1 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-5.3-Codex-Spark when coding workflow support and broader provider choice are central to the workload. Choose Phi-4 Reasoning Vision 15B when vision-heavy evaluation 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
Is GPT-5.3-Codex-Spark or Phi-4 Reasoning Vision 15B open source?
GPT-5.3-Codex-Spark is listed under Proprietary. Phi-4 Reasoning Vision 15B is listed under MIT. 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-5.3-Codex-Spark or Phi-4 Reasoning Vision 15B?
Phi-4 Reasoning Vision 15B 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, GPT-5.3-Codex-Spark or Phi-4 Reasoning Vision 15B?
Phi-4 Reasoning Vision 15B 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 function calling, GPT-5.3-Codex-Spark or Phi-4 Reasoning Vision 15B?
GPT-5.3-Codex-Spark has the clearer documented function calling signal in this comparison. If function calling is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Which is better for tool use, GPT-5.3-Codex-Spark or Phi-4 Reasoning Vision 15B?
GPT-5.3-Codex-Spark has the clearer documented tool use signal in this comparison. If tool use is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Where can I run GPT-5.3-Codex-Spark and Phi-4 Reasoning Vision 15B?
GPT-5.3-Codex-Spark is available on OpenAI API. Phi-4 Reasoning Vision 15B 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.