OpenAI’s Build Week Puts Codex at the Center of a Global Hackathon

OpenAI is hosting Build Week, a July 13–21, 2026 online challenge that asks developers, creators, founders, and students to build projects with Codex.

A public challenge built around Codex

OpenAI’s Build Week page describes the event as a global week of building with Codex, with participants submitting projects during the July 13–21 window. The company frames the challenge broadly, inviting developers, creators, founders, and students to take part.

The public Devpost page for OpenAI Build Week provides more operational detail. Devpost lists the event as an online public hackathon with 28,626 participants, $100,000 in cash prizes, and project requirements tied to Codex and GPT-5.6. The same Devpost page says submissions must include a code repository URL, making a public or shareable repository part of the formal submission workflow.

That repository requirement is notable because Codex, OpenAI’s coding assistant environment, is also documented as operating under sandbox and approval constraints. OpenAI’s ChatGPT Learn documentation on sandboxing says commands such as git inherit workspace boundaries, and that Codex asks before network access or before working outside the workspace.

Security controls are part of the product context

OpenAI’s sandboxing documentation presents these restrictions as a safety boundary rather than a bug. The document says Codex can run commands in a sandboxed environment and that operations involving network access or locations outside the workspace require confirmation.

OpenAI’s public Codex repository on GitHub also includes a reviewer policy document for Codex’s Rust core. That policy classifies some git operations and untrusted external destinations as risk-relevant, which helps explain why repository-related actions can be subject to review, escalation, or blocking depending on context.

Taken together, the official Build Week materials and Codex documentation show a tension common to AI-assisted software development: the same tool is being promoted for rapid project creation while also enforcing boundaries around filesystem access, network use, and version-control operations.

What participants should expect

For Build Week participants, the practical takeaway is that repository setup and submission are part of the published challenge requirements, but Codex may still apply security checks to commands that touch git, remote destinations, or locations outside the active workspace.

The Devpost page’s requirement for a code repository URL does not by itself specify how participants must create or host that repository. OpenAI’s sandboxing documentation indicates that, inside Codex, some steps may require user approval if they involve network access or operations beyond the workspace. Participants who plan to submit should therefore allow time for repository creation, permission prompts, and any manual steps needed outside the Codex environment.

A useful test of agentic coding workflows

Build Week is not only a hackathon; it is also a public test of how Codex fits into real development workflows that include building, version control, publishing, and submission. OpenAI’s own materials emphasize Codex as the central tool for the event, while its documentation makes clear that agentic coding remains bounded by security controls.

That combination may frustrate some users in edge cases, especially when a hackathon requires a repository but the coding environment treats certain repository actions as sensitive. Still, the available OpenAI and Devpost sources support a more precise conclusion: Build Week encourages participants to build with Codex, and Codex is designed to gate certain git, network, and workspace-crossing actions for security reasons.