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.
Further reading
Muse is Meta's new proprietary multimodal reasoning and agent family. Muse Spark 1.1 powers Meta AI and succeeds Llama as Meta's actively promoted assistant model line.
Meta introduced Muse Spark in April 2026 as the first model from Meta Superintelligence Labs' ground-up Muse series. It is a natively multimodal reasoning model with tool use, visual reasoning, and multi-agent orchestration. Muse Spark 1.1, announced in July 2026, adds planning and action capabilities across research, productivity, and connected applications. It powers Meta AI and is available through Meta's products, with API access offered in private preview rather than as open weights.
Further reading
Grok