Grok 4 Heavy

Grok 4 Heavy was released by SpaceXAI on Wednesday, Jul 9 2025.

Grok 4 Heavy was built by SpaceXAI. Elon Musk's AI company building the Grok series of models. Founded in 2023 as xAI, now part of SpaceX. Cursor (Anysphere) and its Composer coding models were acquired in 2026 and are tracked here.

No. Grok 4 Heavy is a closed model. The weights are not published — it is available only through the provider's own API, apps, or partner platforms.

SpaceXAI's previous tracked release was Grok 4 on Jul 9 2025. It was followed by Grok 2.5 on Aug 23 2025.