Harness
Who uses Codex
4 people list Codex as their harness, 4 more use it alongside something else. Newest evidence: Thibault Sottiaux, Jul 12, 2026.
Thibault Sottiaux
OpenAI Codex lead
HarnessCodex
ModelGPT-5.6 Sol
Works at a lab
Aidan McLaughlin
AI researcher, OpenAI core models
HarnessCodex
Model–
Works at a lab
Alexander Embiricos
OpenAI Codex product lead
HarnessCodex
Model–
Works at a lab
Greg Brockman
President and co-founder, OpenAI
HarnessCodex
ModelGPT-6 Astra
Works at a lab
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Also in the mix
- Amjad Masad · Comparison point he says Replit is faster than.
- Dan Shipper · Used alongside Claude Code across Every.
- Mario Zechner · Named as one of the available model/provider options around Pi.
- Theo Browne · Uses the Codex harness inside T3 Code and as a primary harness in the May 2026 workflow.