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AI Productivity & Collaboration

Codex

OpenAI's coding-focused agent environment, with GPT-5.5 as the default model since April 2026

#Codex#OpenAI Codex#GPT-5.5 Codex#coding agent#AI coding tool

What is Codex?

Codex is OpenAI's coding-focused agent environment. It is designed for the model to act autonomously — writing and debugging code, researching, generating documentation, and moving between tools until a task is finished.

What changed recently?

On April 23, 2026, Codex switched its default model to GPT-5.5. The Codex context window is set at 400K tokens, and the runtime is hosted on NVIDIA GB200 NVL72 infrastructure.

How is it used?

Codex is available to Plus, Pro, Business, Enterprise, Edu, and Go users. It excels at multi-step autonomous tasks — cloning a repository, installing dependencies, running migrations, getting tests green — where the model decides the next step on its own without continuous human prompting.

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