Microsoft's[1] Azure AI Foundry blog post "Introducing Phi-4" is dated Dec 12, 2024, the Hugging Face[4] model card gives a release date of December 12, 2024 and the technical report was submitted to arXiv[5] the same day; the open weights followed on January 8, 2025 and OpenRouter[2] lists it from Jan 10, 2025.
Microsoft introduces Phi-4, a 14B-parameter small language model trained mostly on synthetic data that scores 91.8 on November 2024 AMC 10/12 math tests, ahead of Gemini Pro 1.5 at 89.8, on Azure AI Foundry; open MIT-licensed weights follow on 8 January 2025.