Grok 4.3 beta became available on April 17 to SuperGrok Heavy subscribers, priced at $300 per month. On Grok.com, the model appears in the dropdown menu with an “Early Access” label. Users on the regular $30 SuperGrok plan can see it, but cannot turn it on.
The release adds support for PDF, PPT, and Excel generation, along with video input and stronger reasoning features. Its context window jumps from the previous 128K to 2M tokens, a major increase in usable context size.
Musk Pushes Back on the 1T Claim
On April 18, X user Mark Kretschmann posted that Grok 4.3 beta was running with 1T parameters, saying it was twice the size of Grok 4.20 and had been trained for longer. A few hours later, Elon Musk replied in the same thread and said the current 4.3 beta is still 0.5T, describing it as an updated training checkpoint.
Musk also said the real 1T flagship model is five days away from completing its initial training run. He added that the model is expected to deliver a step-change in coding, long-context handling, and other capabilities.
Colossus 2 Is Running Seven Models at Once
According to Musk, the SpaceXAI Colossus 2 model factory is now operational and training seven models at the same time. That lineup includes two 1T models, two 1.5T models, one 6T model, one 10T model, plus the Imagine V2 image model. The 10T pretraining run is expected to take another two months.
Grok Computer Rolls Out Alongside the Model
xAI also introduced Grok Computer alongside Grok 4.3 beta. The product is a PC agent that can operate applications, fill out forms, and complete multi-step desktop tasks. In this setup, Grok 4.3 serves as the reasoning engine, while Grok Computer acts as the execution layer. A wider beta has already opened to some SuperGrok accounts.