GPT-5.3-Codex-Spark vs Phi-4 Reasoning Vision 15B
GPT-5.3-Codex-Spark (2026) and Phi-4 Reasoning Vision 15B (2026) are agentic coding models from OpenAI and Microsoft Research. 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 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.
Phi-4 Reasoning Vision 15B is safer overall; choose GPT-5.3-Codex-Spark when coding workflow support matters.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-02-12 | 2026-03-12 |
| Context window | 131K | — |
| Parameters | — | 15B |
| Architecture | decoder only | - |
| License | Proprietary | Microsoft Research |
| Knowledge cutoff | - | - |
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 | No |
| Multimodal | No | Yes |
| Reasoning | No | No |
| Function calling | Yes | No |
| Tool use | Yes | No |
| Structured outputs | Yes | No |
| Code execution | Yes | No |
Benchmarks
No shared benchmark rows are currently sourced for this pair.
Deep dive
The capability footprint differs most on 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 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
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 Microsoft Research. 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 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.
Which is better for structured outputs, GPT-5.3-Codex-Spark or Phi-4 Reasoning Vision 15B?
GPT-5.3-Codex-Spark has the clearer documented structured outputs signal in this comparison. If structured outputs 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: 2026-05-10. Data sourced from public model cards and provider documentation.