Grok open source: which models you can actually download

Open status at a glance

SpaceXSI (formerly xAI) has released weights for two Grok models and the source code for one tool. Everything newer, including the current Grok 4.7, is closed and only reachable through Grok apps, Cursor or the paid API.

Grok-1: the first open release

Grok-1 was first shown on November 3, 2023, as a preview for X Premium subscribers. On March 17, 2024, xAI published its weights under the Apache 2.0 license, which allows commercial use, changes and redistribution.

Grok-1 is a 314-billion-parameter mixture-of-experts model. In that design, only some specialized parts of the network switch on for each token, which cuts compute cost. The release was the base model, not the tuned chatbot people used on X. It is now far behind current Grok models, but it remains the only Grok model released under a standard open-source license.

Grok 2.5: open weights with strings attached

On August 23, 2025, Musk announced that Grok 2.5 was available on Hugging Face. The weights are public, but the license is a custom one with acceptable-use limits on commercial use. That makes Grok 2.5 “source-available” rather than open source in the sense used by the Open Source Initiative.

As of October 12, 2026, SpaceXSI’s Hugging Face organization lists only grok-1 and grok-2, according to the same tracker.

The Grok 3 promise that was missed

In August 2025, when Grok 2.5 came out, Musk said Grok 3 would be open-sourced in about six months. That would have meant roughly February 2026. It did not happen. Grok 3 was instead retired from the API on May 15, 2026, and its weights have not been published as of October 18, 2026.

The pattern matters if you plan around Musk’s open-source dates. Releases have come, but on a slower and less predictable schedule than announced.

Grok Build: open code, not open weights

On July 15, 2026, SpaceXSI published the full source of Grok Build, its terminal coding agent, at github.com/xai-org/grok-build. First-party code is under Apache 2.0, and third-party code keeps its own licenses. The repo had about 27.4k stars and 5.2k forks when we checked.

This was not a model release. Grok Build is the program that calls Grok models; the models themselves stay closed. The release followed a July 2026 incident in which the tool could upload whole directories to company cloud storage. SpaceXSI said the source went public to rebuild trust. Some outlets give the date as July 16, which is the press date. The x.ai news post is dated July 15.

External contributions to the repo are not accepted.

The promised 0.5T model

On May 25, 2026, Musk said SpaceXSI would open-source “the 0.5T model” toward the end of 2026. The name suggests about half a trillion parameters, but no official specs, license or date have been published. As of October 18, 2026, it is still pending.

For comparison, Musk has described Grok 4.7 as about 2.1T parameters and the unreleased Grok 4.8 as about 2.5T. Those figures are his statements, not official specs. We follow future model news on our Grok 5 tracker and list every release on the Grok models page.

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