On Thursday, OpenAI announced the release of a light-weight version of its agent coding tool Codex, the latest model of which OpenAI launched earlier this month. GPT-5.3-Codex-Spark is described by the company as a “minor version” of that model, one designed for faster inference. To enable that inference, OpenAI brought in a dedicated chip from its hardware partner Cerebras, marking a new level of integration with the company’s physical infrastructure.

the Fellowship between Cerebras and OpenAI was announced last month, when OpenAI said that it reached a multi-year agreement with the company worth more than $10 billion. “Integrating Cerebras into our mix of compute solutions is all about making our AI more responsive,” the company said at the time. Now, OpenAI calls Spark the “first milestone” in that relationship.

Spark, which OpenAI says is designed for speed, real-time collaboration and “rapid iteration,” will be powered by Cerebras’ Wafer Scale Engine 3. WSE-3 is Cerebras’ third generation waferscale megachip, adorned with 4 trillion transistors. OpenAI describes the new lightweight tool as a “daily productivity driver, helping users with rapid prototyping” rather than the longer, heavier tasks the original 5.3 was designed for. Spark is now enjoying a research preview for ChatGPT Pro users in the Codex app.

In one tweet before the announcement, CEO Sam Altman seemed to introduce the new model. “We have something special rolling out to Codex users on the Pro plan later today,” Altman tweeted. “It brings joy to me.”

In its official statement, OpenAI emphasized that Spark was designed for the lowest possible latency in Codex. “Codex-Spark is the first step towards a Codex that works in two complementary modes: real-time collaboration when you want fast iteration, and long-term tasks when you need deeper reasoning and execution,” shared OpenAI. The company added that Cerebras’ chips excel in helping “workflows that demand extremely low latency.”

Cerebras are all around for more than a decade but, in the era of AI, it has enjoyed a more prominent role in the tech industry. Last week, the company announced that it raised $1 billion in new capital at a cost of $23 billion. The company has previously announced his intentions to pursue an IPO.

“What excites us most about GPT-5.3-Codex-Spark is the collaboration with OpenAI and the developer community to discover what rapid communication is possible – new interaction patterns, new use cases, and a fundamentally different experience model,” Sean Lie, CTO and co-founder of Cerebras, said in a statement. “This preview is just the beginning.”