OpenAI Won't Release a GPT-5.5-Codex Model

· ai · Source ↗

TLDR

  • OpenAI’s Romain Huet confirms GPT-5.5-Codex won’t exist: Codex merged into the main model line starting with GPT-5.4.

Key Takeaways

  • Since GPT-5.4, OpenAI unified Codex and the main GPT model into a single system; no separate coding model remains.
  • GPT-5.5 extends this unified architecture with reported gains in agentic coding, computer use, and general on-computer tasks.
  • The dedicated Codex product line is discontinued as a separate release track.
  • Romain Huet, head of developer experience at OpenAI, made the statement directly.

Why It Matters

  • Developers who planned around a distinct Codex model should expect agentic coding capabilities to ship inside the main GPT-5.x line instead.
  • The merge signals OpenAI is betting that a single generalist model can match or exceed a specialist coding model, with no public benchmark disclosed yet.
  • Any tooling or prompt strategy tuned to Codex-specific behavior or endpoints may need to be retargeted to the unified GPT-5.x API.

Simon Willison / Simon Willison’s Weblog · 2026-04-25 · Read the original

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