FastChat vs. GLM

Overview

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.

Initial release: 2023-04-28

Reference

https://github.com/lm-sys/FastChat

Further Reading

• https://chat.lmsys.org/
• https://lmsys.org/projects/

Overview

GLM is Z.ai's open-weight model family for reasoning, coding, agents, and long-horizon work. GLM-5.2 is the current generation with a one-million-token context window.

The GLM family began with bilingual pretrained models and evolved through the ChatGLM and GLM-4 generations. GLM-5 scaled the mixture-of-experts architecture to 744B total parameters with 40B active parameters. GLM-5.2, released in June 2026, adds a stable one-million-token context window, stronger long-horizon coding and agent performance, adjustable reasoning effort, and efficiency improvements for sparse attention. Its weights are available under the MIT license.

Initial release: 2022-08-04

Current generation: GLM-5.2

Reference

https://z.ai/blog/glm-5.2

Further Reading

• https://z.ai/blog/glm-5
• https://z.ai/blog/glm-5.2
• https://huggingface.co/zai-org