OpenAI Brings the Codex App to Windows With a New Native Sandbox

According to Neowin, OpenAI has officially launched the Codex app for Windows, bringing its coding agent experience to Microsoft’s desktop ecosystem after the macOS debut last month. The release also follows GPT-5.3-Codex, the model the app uses to run agent-driven coding tasks.

Codex arrives on Windows through the Microsoft Store

Developers can download the Codex app now through the Microsoft Store. OpenAI positions the Windows release as a native experience that fits into existing workflows, without forcing developers to abandon familiar tools.

A Windows-native sandbox keeps agents contained

OpenAI faced a core Windows challenge: stopping AI agents from gaining broad access to the local file system. To address it, OpenAI built its first Windows-native agent sandbox in collaboration with Microsoft, relying on OS-level security controls such as restricted tokens, filesystem ACLs, and dedicated sandbox isolation.

This approach aims to let agents operate inside Windows development environments, including PowerShell, while limiting what they can touch.

Open-sourcing the sandbox could enable similar apps

OpenAI has also open-sourced the sandbox, which could let other companies build comparable agent apps for Windows using the same isolation approach. That move could also accelerate the adoption of safer, Windows-native execution environments for agent-based tools.

Parallel coding agents and review-first workflows

Like the macOS version, the Windows Codex app lets developers run multiple coding agents at the same time while keeping tasks separated. Each agent runs inside its own isolated worktree to avoid conflicts, and the app supports diff inspection and review before changes get merged.

It also supports switching between tasks and projects, reusable skills built on tools and scripts, automation for repetitive workflows, and integration with Codex CLI and IDE extensions to preserve existing setups.

To mark the Windows launch, OpenAI now lets ChatGPT Free and Go users try Codex, while Plus, Pro, Business, Enterprise, and Edu users receive double rate limits until April 2.

In other news, OpenAI has released GPT-5.3 Instant, and the company is allegedly working on its own GitHub alternative.