Described by OpenAI as its first model instrumental in creating itself. It is the successor to GPT-5.2-Codex in the Codex line, reaching state of the art on SWE-Bench Pro and taking the Terminal Bench 2.0 record at 77.3% less than thirty minutes after Opus 4.6 set it at 65.4%. In this corpus its launch is the moment the recursion enters a frontier lab’s own release notes, three days after a Codex manager said the product builds itself.
AISystem
GPT-5.3-Codex
OpenAI's February 2026 coding model, described in its own launch copy as the first model instrumental in creating itself.
Sources
Attribution and reporting linked by this record; links do not imply independent verification.
- Welcome to February 6, 2026 (theinnermostloop.substack.com)
Development timeline
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