Grok vs. OPT

Overview

Grok is the proprietary model family available through xAI's products and API. Grok 4.5 is the current generation, focused on coding, agentic tasks, reasoning, and knowledge work.

xAI introduced Grok in November 2023 and released the weights for Grok-1 under Apache 2.0 in March 2024. Later generations are proprietary and available through Grok, X, and the xAI API. Grok 4.5, released in July 2026, is xAI's current flagship model for software engineering, tool-driven agents, complex reasoning, and professional knowledge work.

Initial release: 2023-11-05

Current generation: Grok 4.5

Reference

https://x.ai/news/grok-4-5

Further Reading

• https://github.com/xai-org/grok-1/tree/main
• https://x.ai/news/grok-4-5

Overview

Open Pre-trained Transformer Language Models (OPT) is part of the family of open source models designed to replicate GPT-3, with similar decoder-only architecture. It has since been superseded by models such as LLaMA, GPT-J, and Pythia.

Initial release: 2022-05-03

Reference

https://github.com/facebookresearch/metaseq/tree/main/projects/OPT

Further Reading