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Thibault Sottiaux

Head of Codex (OpenAI's title for Sottiaux in May 2026), OpenAI

  • Head of Codex (OpenAI's title for Sottiaux in May 2026), OpenAI12

Thibault "Tibo" Sottiaux leads Codex, OpenAI's software engineering agent, and is listed by OpenAI as its Head of Codex. Before OpenAI, Sottiaux led human data work for Gemini at Google DeepMind and built AI/ML workflow infrastructure for DeepMind research, after earlier work as a software engineer at Google. Sottiaux is also a hands-on contributor to the open-source Codex project and a co-author of OpenAI research on verifying code at scale.1234

At a glance

Current role
Head of Codex (OpenAI's title for Sottiaux in May 2026)
Company
OpenAI
Sources cited
9
Profile reviewed

Accomplishments

  • Leads Codex, OpenAI's software engineering agent, as Head of Codex.12
  • Contributes code to the open-source Codex project, with pull requests merged from April 16, 2025, including rate-limit retries with exponential back-off.3
  • Added experimental support for skills to Codex in December 2025.5
  • Co-authored OpenAI research on a dedicated agentic code reviewer for Codex models.4
  • Led human data work for Gemini at Google DeepMind.1
  • Built AI/ML workflow infrastructure for DeepMind research and co-authored Reverb, an experience replay system for reinforcement learning.167
  • Shared how Codex is growing beyond software engineering in an OpenAI Forum session in May 2026.1

Education and early career

Sottiaux holds degrees in computer science, computational mathematics, and applied mathematics from the Université catholique de Louvain (UCLouvain). Earlier in Sottiaux's career, Sottiaux worked as a software engineer at Google and in applied research roles.1

Research infrastructure and Gemini at Google DeepMind

At DeepMind, Sottiaux built AI/ML workflow infrastructure for DeepMind research. In February 2021 Sottiaux was one of seven co-authors, with colleagues from DeepMind and Google Research, of the paper introducing Reverb, an efficient, extensible, and easy-to-use system designed for experience replay in reinforcement learning that works in distributed configurations. Reverb is published on GitHub by Google DeepMind as a data storage and transport system for machine learning research.167

Sottiaux also led human data work for Gemini at Google DeepMind.1

Leading Codex at OpenAI

At OpenAI, Sottiaux is a Member of Technical Staff who leads Codex, OpenAI's software engineering agent, and the OpenAI Forum lists Sottiaux as Head of Codex. OpenAI describes Sottiaux's work as building AI systems that help developers understand codebases and complete engineering tasks.12

Sottiaux also writes code for Codex in the open. In the public openai/codex repository, home of the Codex coding agent that runs in a developer's terminal, Sottiaux's pull requests began merging on April 16, 2025, with early changes that added retries and exponential back-off for rate-limit errors and more native keyboard navigation in the multiline editor. On December 2, 2025, Sottiaux added experimental support for skills to Codex.8359

On December 1, 2025, Sottiaux and Codex team colleagues published "A Practical Approach to Verifying Code at Scale" on OpenAI's alignment research blog. It describes a dedicated agentic code reviewer trained for OpenAI's Codex models, given repo-wide tools and execution access, and explains why reviewer precision matters for adoption and why verification is often cheaper than generation. The reviewer is deployed on internal and external GitHub traffic.4

Codex beyond code

On May 13, 2026, Sottiaux joined an OpenAI Forum conversation, "Codex is for Everyone: Why Codex Matters Beyond Code," on how Codex is evolving from a coding tool for developers, what the team is learning from the people who use it, and why agentic tools matter beyond software engineering, for audiences from leaders and researchers to educators and small business owners.12

Timeline

  1. Co-authored the paper introducing Reverb, DeepMind's framework for experience replay.67
  2. First pull requests merged into the open-source openai/codex repository.3
  3. Co-published OpenAI research on verifying code at scale with an agentic code reviewer.4
  4. Added experimental support for skills to Codex.5
  5. Spoke as Head of Codex at the OpenAI Forum session "Codex is for Everyone."12

Other documented roles

Roles the sources document that are not confirmed as current.

  • Led human data work for Gemini; built AI/ML workflow infrastructure for DeepMind research, Google DeepMind16
  • Software Engineer, Google1

Where they work

Suggest a correction or removal

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References

9 sources · profile reviewed Oct 11, 2026 · data updated Oct 11, 2026

  1. Codex is for Everyone: Why Codex Matters Beyond CodeOpenAI Forum (OpenAI) · Official page · accessed Oct 11, 2026
  2. Event Replay: Codex is for Everyone: Why Codex Matters Beyond CodeOpenAI Forum (OpenAI) · Official page · published May 14, 2026 · accessed Oct 11, 2026
  3. Pull requests by tibo-openai in openai/codexGitHub (OpenAI) · Other · accessed Oct 11, 2026
  4. A Practical Approach to Verifying Code at ScaleOpenAI Alignment Research Blog · Paper · published Dec 1, 2025 · accessed Oct 11, 2026
  5. Commits by tibo-openai in openai/codexGitHub (OpenAI) · Other · accessed Oct 11, 2026
  6. Reverb: A Framework For Experience ReplayarXiv (DeepMind and Google Research authors) · Paper · published Feb 9, 2021 · accessed Oct 11, 2026
  7. google-deepmind/reverbGitHub (Google DeepMind) · Documentation · accessed Oct 11, 2026
  8. openai/codexGitHub (OpenAI) · Documentation · accessed Oct 11, 2026
  9. Thibault Sottiaux (tibo-openai) on GitHubGitHub (Thibault Sottiaux's profile) · Official page · accessed Oct 11, 2026