Meet the OpenAI Engineer Leading ChatGPT's Biggest Transformation Yet

Overview

OpenAI has handed Thibault Sottiaux, the engineer who built its Codex coding tool into one of the company's fastest-growing products, responsibility for the biggest redesign of ChatGPT since its launch. Codex passed 5 million weekly active users by early June 2026, about six times its level when the desktop app shipped in February 2026. His mandate centers on personalization, memory across sessions, and smarter defaults so people need less careful prompting.

Key Takeaways

Thibault Sottiaux, the technical lead behind OpenAI's Codex coding tool, now leads a broad redesign of ChatGPT described as its biggest change since launch.
His earned credential is Codex growth: the product reached more than 5 million weekly active users by early June 2026, roughly six times its February 2026 level.
The ChatGPT overhaul targets three things: personalization, memory that carries across sessions, and smarter defaults so users prompt less carefully.
The plan reflects OpenAI's wider view that the future is agents completing tasks, not chatbots only answering questions.
Codex is spreading beyond engineers, with knowledge workers now close to 20 percent of users and growing more than three times faster than developers.
The redesign coincides with OpenAI consolidating ChatGPT, Codex, and its developer API under one core product structure as competition intensifies.

Stats & Key Facts

#More than 5 million weekly active users for Codex by early June 2026, a measure of its scale.
#About six times growth in Codex weekly active users since the desktop app launched in February 2026.
#Close to 20 percent of Codex users are now knowledge workers rather than developers.
#Knowledge-worker adoption of Codex is growing more than 3 times faster than developer adoption.
#Anthropic's Claude Code reached an estimated 2.5 billion dollar annualized revenue run rate by February 2026, a competitive benchmark.

Who Thibault Sottiaux Is and Why OpenAI Picked Him

The appointment rewards a track record built on one of OpenAI's standout products.

Thibault Sottiaux is the technical lead who turned Codex, OpenAI's AI coding tool, into one of the company's fastest-growing products. That success is the reason OpenAI gave him a much larger assignment: reshaping ChatGPT, the app that made the company a household name.

His selection is a signal about method. Codex grew by understanding how developers work and fitting into their daily workflow rather than acting as a generic question-and-answer box. OpenAI wants that same disciplined, workflow-first thinking applied to its consumer chatbot.

The Codex Numbers Behind the Promotion

Growth figures explain why OpenAI trusts Sottiaux with its flagship product.

›Codex passed 5 million weekly active users by early June 2026.
›That base is roughly six times its size when the Codex desktop app shipped in February 2026.
›Knowledge workers now make up close to 20 percent of Codex users.
›Adoption among knowledge workers is growing more than three times faster than among developers.

What the ChatGPT Redesign Aims to Fix

The overhaul targets long-standing complaints about the consumer app.

ChatGPT serves a very large audience but has drawn criticism for inconsistent answers, a confusing interface, and a feature set that grew cluttered over time. Sottiaux's job is to bring order to that messier consumer setting.

Three goals define the work. First, personalization, so the app adapts to the individual user. Second, memory that carries across sessions, so people do not repeat context each time. Third, smarter defaults, so good results no longer depend on writing careful prompts.

From Chatbot to Personal Agent

The redesign reflects a bigger strategic shift inside OpenAI.

OpenAI increasingly frames its future around agents that complete tasks, not chatbots that only respond to questions. Sottiaux has described the aim as a personal agent helping across both work and everyday life, extending past any single app.

Reporting on the reorganization indicates OpenAI is consolidating ChatGPT, Codex, and its developer-facing API into a more unified product structure. The intent is to apply the same agent-style approach across the whole lineup rather than treating each tool as a separate experience.

The Competitive Stakes With Anthropic

Rivals are pressing hard in exactly the area Sottiaux knows best.

›Anthropic's Claude Code reached an estimated 2.5 billion dollar annualized revenue run rate by February 2026.
›AI coding has become a fiercely contested market, the same ground where Codex grew.
›Winning the consumer app while defending the coding business raises the stakes on Sottiaux's appointment.

What This Means for Everyday ChatGPT Users

For non-technical readers, the practical question is whether ChatGPT gets easier to use.

If the redesign succeeds, ChatGPT should feel more like a tool that remembers your preferences and needs less hand-holding to give useful answers. The promise is fewer prompt tricks and more consistent results out of the box.

The open question is scale. Codex serves millions of users, but ChatGPT serves a far larger base measured in hundreds of millions. Whether engineering-led product thinking holds up at that size is the real test Sottiaux now owns.

Frequently Asked Questions

Who is Thibault Sottiaux?

He is the OpenAI engineer who served as technical lead for Codex, the company's AI coding tool. OpenAI has now put him in charge of a broad redesign of ChatGPT.

How big has Codex become?

Codex reached more than 5 million weekly active users by early June 2026. That is about six times its size when the desktop app launched in February 2026.

What is changing in ChatGPT?

The redesign focuses on personalization, memory that carries across sessions, and smarter defaults so users get good results without careful prompting. It is described as the biggest change to ChatGPT since its launch.

Why does OpenAI care about agents over chatbots?

OpenAI believes the future is AI that completes tasks rather than only answering questions. Codex's workflow-based design is the model it wants to bring to ChatGPT and across its products.

How does this connect to competition with Anthropic?

AI coding is a contested market, and Anthropic's Claude Code reached an estimated 2.5 billion dollar annualized revenue run rate by February 2026. OpenAI is defending that business while trying to upgrade its consumer app at the same time.

OpenAI is wagering that the methods that grew Codex into a top product will translate to its flagship chatbot. The test is whether engineering-led design holds up for an app used by hundreds of millions.

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