TL;DR
- Windows Launch: OpenAI released the Codex AI coding app for Windows on March 4, 2026, after more than 500,000 developers joined the waitlist.
- Native Sandbox: The Windows version ships with an open-source native agent sandbox using OS-level isolation, built in collaboration with Microsoft.
- Key Features: The app supports parallel agent tasks, PowerShell integration, per-task worktrees with diff review, and cross-platform session continuity.
- Launch Promotions: Paid ChatGPT subscribers receive double the Codex rate limit through April 2, 2026, while Free and Go users can try Codex for the first time.
macOS got Codex last month. Windows needed more work: OpenAI had to engineer a new native sandbox with OS-level isolation before it could bring its AI coding agent to the Microsoft Store.
Released Wednesday, March 4, the Codex app is now on Windows and available from the Microsoft Store, backed by demand from more than 500,000 developers on the Windows waitlist and a Mac app that was downloaded more than 1 million times in its first week.
The Codex app is now on Windows.
Get the full Codex app experience on Windows with a native agent sandbox and support for Windows developer environments in PowerShell.https://t.co/Vw0pezFctG pic.twitter.com/gclqeLnFjr
— OpenAI Developers (@OpenAIDevs) March 4, 2026
What the Windows App Offers
That demand shaped what the Windows version delivers in practice. Developers can run multiple agents in parallel across long-running tasks and manage diffs from a single interface, without switching to WSL or virtual machines. The app ships with a native agent sandbox using OS-level controls and includes full PowerShell support for Windows developer environments.
Each task runs in its own worktree, letting users inspect diffs before merging changes to the codebase. Session history is saved to the OpenAI account, so developers can pick up on Windows without losing work.
By default the app uses the native Windows sandbox, though WSL support is also available for teams that prefer Linux tooling. Cross-platform continuity reduces friction for teams where Windows dominates corporate desktops and Mac is prevalent among individual developers.
Skills, Models, and CLI Integration
Beyond parallel task management, the Windows app extends Codex’s model and skill ecosystem. The Windows release ships with Windows-specific skills, including a WinUI skill for developers building Windows applications. OpenAI introduced the Skills framework to Codex CLI: shareable, composable instruction sets that steer agent behavior across projects and integrations.
The app also picks up history and configuration from the Codex CLI, which has been available since April 2025, and from IDE extensions, preserving workflow context as developers move to the GUI.
The default model is the GPT-5.3-Codex model, with options to switch to GPT-5.2-Codex, GPT-5.1-Codex-Max, and GPT-5.1-Codex-Mini for lightweight tasks. Users can configure the reasoning level per model. The tiered lineup positions Codex to serve both developers who need maximum reasoning capacity and those running high-volume lightweight tasks where cost per token matters.
The Engineering Challenge
Bringing Codex to Windows proved more complex than the macOS launch. The core problem: Codex agents need filesystem access to do their work but must be restricted from reading files outside the designated workspace. OpenAI worked with Microsoft to address this constraint, producing the first Windows-native agent sandbox that enforces OS-level isolation through restricted tokens, filesystem ACLs, and dedicated sandbox users at the process level.
Furthermore, the sandbox implementation is published as open source, with the code available on GitHub for developers who want to inspect the isolation logic directly. The build was designed, per an OpenAI spokesperson, “for real Windows developer environments,” OpenAI told The New Stack, not merely as a compatibility layer on top of Windows. Open-sourcing the sandbox gives enterprise security teams an auditable baseline, a meaningful factor for adoption in regulated industries.
Availability and Launch Promotions
With the sandbox complete and the Store listing live, OpenAI paired the release with promotions to drive early adoption. The Codex app for Windows is available from the Microsoft Store now.
To mark the launch, ChatGPT Free and Go customers can now try Codex for the first time. Meanwhile, ChatGPT Plus, Pro, Business, Enterprise, and Edu subscribers receive double the Codex rate limit through April 2, 2026.
Building on this momentum, Codex has reached 1.6 million weekly active users. Team lead Thibault Sottiaux has described the app as OpenAI’s standard agent, with plans for enterprise deployments that extend to non-technical workers over time. For developers who have been on the waitlist, the rate-limit doubling through April 2 provides a near-term opportunity to evaluate Codex before standard limits resume.
