Computer and browser use in Codex (5 real examples)

2026-07-22 · Source: Lenny's Newsletter · Field: Technology & Digital — Artificial Intelligence & Machine Learning, Software Development & Engineering · Depth: Intermediate, extended

Summary

The article demonstrates how to utilize AI, specifically the Codex (now ChatGPT) desktop app and Chrome extensions, for advanced browser and computer automation. It showcases five real-world examples, including using AI for exhaustive quality assurance of web applications, such as validating onboarding flows, testing responsive design, and identifying 11 issues, including one high-severity navigation blocker. The AI can also perform persona-based application testing, impersonating roles like a product manager or engineer to provide research-style critique. Other practical applications include managing LinkedIn messages, curating personal shopping carts (e.g., 10 sale items totaling \$352 from Free People), filling out complex forms, remotely controlling a phone via iPhone mirroring for tasks like Wi-Fi management, and generating Google Docs or Sheets. A key technique highlighted is "under-prompting" frontier models for superior results.

Key takeaway

For AI Product Managers or Software Engineers seeking to enhance testing efficiency, you should integrate AI desktop apps like Codex with browser extensions into your QA workflows. This approach allows for exhaustive, persona-based application testing and responsive design validation, surfacing edge-case bugs you might miss. Consider "under-prompting" frontier models to let them devise comprehensive test plans. This can significantly reduce manual toil and accelerate your development cycles.

Key insights

AI desktop apps with browser extensions can automate complex digital tasks across various personal and professional domains.

Principles

• Under-prompt frontier models for better outcomes.
• AI testing is more exhaustive and organized than human QA.
• Combine browser use with persona-based prompts for deeper app critique.

Method

Install the ChatGPT or Claude desktop app and official Chrome extensions. Invoke browser use via "@browser", "@Chrome", or "@computer" commands within the AI chat interface.

In practice

• Automate web app QA and responsive design testing.
• Manage social media messages and replies.
• Curate shopping carts based on specific criteria.

Topics

• AI Desktop Automation
• Browser Automation
• Computer Control
• Web Application QA
• Persona-Based Testing
• Codex AI
• Under-prompting

Best for: Software Engineer, AI Engineer, AI Product Manager

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Editorial summary, takeaway, and curation by AIssential. Original article published by Lenny's Newsletter.