Debug Web Apps with Browser Use in Codex

Why It Matters

By enabling CDP, Codex can diagnose real-world performance and network issues directly in running applications, speeding root-cause identification and more reliable fixes—potentially reducing developer debugging time and improving app performance. This narrows the gap between AI-assisted coding and practical, observable QA for web developers.

Summary

OpenAI's Codex now integrates the Chrome DevTools Protocol (CDP) into its Browser Use feature, giving it access to advanced debugging tools like performance profiling, network inspection, console logs, runtime errors, local storage, and applied styles. Users must enable Developer Mode in their Codex app and explicitly approve CDP access before Codex can inspect a website. In a demo, Codex profiled a sluggish chat app, identified performance bottlenecks via network and runtime inspection, applied fixes, and demonstrated measurable improvements. The update extends Codex's capabilities from static code review to interactive, data-driven debugging of live web apps.

Original Description

Codex can now use the Chrome DevTools Protocol (CDP) in Browser Use to inspect console logs, runtime errors, local storage, applied styling, network traffic, and performance profiles while working on web applications.

In this demo, Codex investigates a slow chat app by profiling interactions and inspecting network requests, then fixes the issues and supports the changes with clear measurements.

To use this functionality, enable Developer mode in the Browser settings of your Codex app and approve CDP access when Codex starts inspecting a website.

Learn more here: https://developers.openai.com/codex/app/browser#developer-mode

Chapters:

00:00 CDP support in Browser Use

00:23 Enable Developer Mode and approve access

00:37 Debugging a slow chat app

00:56 Profiling real bottlenecks

01:15 More in-depth browser capabilities