Inside OpenAI’s fast-growing Codex: The people building the AI that codes alongside you

OpenAI leaders reveal how the company’s rapidly growing coding agent works, why developers are delegating tasks to it, and what that means for the future of software work.

[Screenshots: OpenAI]

OpenAI’s Codex AI coding assistant is having a growth spurt. OpenAI tells Fast Company that its weekly active users have tripled since the start of the year, while overall usage (measured in tokens) has increased fivefold. The surge is likely driven by the release of new models—GPT-5.2 last December and GPT-5.3-Codex in early February—as well as the launch of Codex’s app version a few weeks ago. OpenAI says the app has been downloaded more than a million times. Across all access points—including the cloud, app, and command line—more than a million developers and other users now rely on Codex at least once a week,........

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