A side-by-side comparison of release history, capabilities, licensing and model sizes.
| Attribute |
 FastChat
|
 Phi
|
|---|---|---|
| Developer | LMSYS | Microsoft |
| Current generation | – | Phi-4 |
| Initial release | 2023-04-28 | 2023-06-20 |
| Instruct tuned | Yes | Yes |
| Coding | No | Yes |
| Finetuning | Yes | Yes |
| Open source | Yes | Yes |
| License | Apache 2.0 | MIT |
| Model sizes | 3B | 3.8B, 5.6B, 14B |
| Links |
FastChat is the open platform for training, serving, and evaluating LLM chatbots developed and maintained by LMSYS.
FastChat is an open-source library for training, serving, and evaluating LLM chat systems from LMSYS. It includes training and evaluation code, a model serving system, a Web GUI, and a finetuning pipeline, and is the de facto system for Vicuna as well as FastChat-T5. FastChat also includes the Chatbot Arena for benchmarking LLMs.
Phi is Microsoft's family of compact open models designed for efficient local and edge deployment. Phi-4 is the current generation.
Microsoft introduced Phi-1 and Phi-2 to demonstrate how carefully curated and synthetic training data can make small models unusually capable. Phi-3 expanded the family for mobile and multimodal use. The Phi-4 generation includes a 14B general model and reasoning variants, plus smaller and multimodal checkpoints. Phi models are released under the MIT license and are designed for research, local inference, and resource-constrained production workloads.
