Phi-4-reasoning

Phi-4-reasoning is a text-only language model in Microsoft's phi family that emphasizes structured chain-of-thought inference, aiming to deliver careful step-by-step reasoning for tasks such as mathematics, programming, and analytical problem solving at a relatively compact scale. Independent hosting references describe it as a causal LM based on the Phi-3 architecture lineage, served through vLLM with an open-weight distribution under the MIT license, and third-party listings place it around 14-15 billion parameters with a 32K-33K token context window. Its design intent is to give practitioners a smaller, openly shareable alternative to much larger frontier systems while still supporting long chain-of-thought traces through sampling at temperature 0.8 with top-k 50 and top-p 0.95.

In qualitative use it fits well for developers and teams that need a locally deployable reasoning model on consumer or single-workstation GPUs, since its context window and parameter footprint are tuned for workloads like code generation, technical Q&A, and step-by-step problem analysis without relying on a frontier cloud provider. Independent listings recommend pairing it with longer max-new-token budgets on complex prompts so the model can lay out extended thinking before arriving at an answer, which aligns with its chain-of-thought focus. It is best viewed as a focused, open reasoning engine rather than a generalist assistant, useful where explainable intermediate steps and open-weight deployment matter more than breadth of modalities.