DeepSeek vs. FastChat

Overview

DeepSeek develops open-weight mixture-of-experts models for reasoning, coding, agents, and efficient long-context inference. DeepSeek V4 is the current generation.

DeepSeek began releasing language models in 2023 with DeepSeek Coder, then gained broad adoption with DeepSeek V3 and the R1 reasoning model in 2024 and 2025. DeepSeek V4, released in April 2026, includes a 284B-parameter Flash model with 13B active parameters and a 1.6T-parameter Pro model with 49B active parameters. Both support one-million-token context windows and are released with open weights under the MIT license.

Initial release: 2023-11-29

Current generation: DeepSeek V4

Reference

https://www.deepseek.com/

Further Reading

• https://api-docs.deepseek.com/news/news260424/
• https://huggingface.co/collections/deepseek-ai/deepseek-v4

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/