OpenAI adds Codex to ChatGPT mobile app as Claude Code rivalry heats up

OpenAI launched Codex integration in the ChatGPT mobile app on Thursday, May 14, giving developers a way to monitor and manage coding workflows from their phones. Per the X post, the update is available now in preview across all ChatGPT plans on iOS and Android devices.

The phone connects to Codex, it does not run it

Codex, the AI coding agent OpenAI first released roughly a year ago, is now available through the ChatGPT app on mobile devices.

The phone does not run Codex locally. Instead, the ChatGPT app acts as a remote interface to whatever environment a developer has already configured, whether that is a physical machine like a Mac mini or a cloud-hosted workspace, according to Engadget.

In essence, files, credentials, and permissions all remain on the machine where Codex is actually running. ChatGPT updates a user’s mobile phone with status updates, screenshots, and test results, and allows them to enter new prompts for subsequent executions.

A relay layer ensures machines are accessible

To ensure that local machines remain reachable across devices, while also securing their identity from the public internet, OpenAI implemented what they called a “secure relay.”

The relay synchronizes active session state and context across all devices where a user is signed into ChatGPT.

A developer can start a Codex task at home or in the office, leave for the day, and get a notification on their phone when the agent needs a decision to continue. To use the feature, developers need to update the ChatGPT app on their phones and the Codex app on their Macs.

OpenAI said Windows support for Codex connection to mobile phones is coming soon.

Codex mobile: A competitive response to Claude Code?

Last month, OpenAI gave Codex the ability to run tasks in the background on desktop. Earlier in May, it shipped a Chrome extension that lets the agent operate in live browser sessions.

On the other side, Anthropic has offered mobile access to its Claude Code tool since last fall through a feature called Remote Control, which lets users monitor agentic coding sessions from their phones.

As Cryptopolitan earlier reported, Codex, at its first launch in ChatGPT in May 2025, was built to handle tasks such as writing features, answering codebase questions, fixing bugs, and proposing pull requests in isolated cloud environments. The new mobile layer update extends that reach without changing the underlying model.

According to TestingCatalog, the absence of native phone control is a common complaint among Codex users on GitHub and the OpenAI developer forum, with some citing it as the reason why they have moved to competing platforms.

Thursday’s release from OpenAI reflects an intensifying contest with Anthropic over which agentic coding platform becomes the default for professional developers. Not just that, it also connects to the company’s broader ambitions for a unified app.

In March, OpenAI confirmed it was building a single desktop application combining ChatGPT, Codex, and its Atlas web browser into one product.

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