OpenAI folds Codex coding model into GPT-5.5, discontinuing separate programming AI

THE DECODER · April 26, 2026

AI Summary

•OpenAI merged its dedicated Codex code-writing model into the main GPT-5.5 language model as of GPT-5.4 (released in early 2025). Version 5.3, shipped in early February, was the last standalone Codex release. This repeats a pattern: OpenAI shut down the original Codex in 2023, then revived it in May 2025 as Codex-1 before folding it back into the main model.
•GPT-5.5 requires fewer tokens (units of text the model processes) than GPT-5.4 to complete the same coding tasks, meaning faster responses and lower computing costs for the same work. However, despite this efficiency gain, OpenAI raised API pricing by approximately 20 percent, so users will pay more overall.
•Developers who rely on dedicated coding AI for programming tasks will now get those features built into GPT-5.5's general-purpose model instead of a separate tool. GPT-5.5 emphasizes agentic coding—where AI autonomously completes coding work with minimal human oversight—and improved ability to control computers, which may shift how teams structure code review and automation workflows.

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