The Ultimate Guide to ChatGPT Codex: OpenAI's Claude Code Killer
Check out the conversation on Apple, Spotify and YouTube.Brought to you by:* Jira Product Discovery: Move discovery and roadmapping out of spreadsheets* Vanta: Automate compliance across 35+ frameworks like SOC 2 and ISO 27001* Kameleoon: Leading AI experimentation platform* NayaOne: Airgapped cloud-agnostic sandbox* Product Faculty: Get $500 off the AI PM Certification with code AAKASH25Today’s EpisodeClaude Code hit $1B ARR in 6 months. But OpenAI is not just giving up.ChatGPT’s new Codex is the most powerful way for product managers to build prototypes. And it’s a far better way to use ChatGPT than the browser.So every PM should know how to use it.Today, I brought back the man behind my Claude Code tutorial, Carl Vellotti, for a full guide on how to use ChatGPT Codex for PMs:This might be the most important podcast you watch all year. (And not a single other PM podcast has even talked about this tool)Your Newsletter Subscriber BonusFor subscribers, each episode I also write up a newsletter version of the podcast. Thank you for having me in your inbox.Today’s guide covers:* Getting Started: The Non-Technical PM’s Guide to Codex CLI* Classic PM Tasks: Documents, Meetings & PRDs with Codex* Advanced Prototyping: From Vibe Coder to Vibe EngineerThis is your complete Codex roadmap.1. How to Get Started - The Non-Technical PM’s Guide to Codex CLIIf you’ve never touched a terminal, this is for you.1a. Open Codex in an IDECarl opens Cursor and shows files Codex creates in real-time.Workflow: Open project folder in Cursor → Terminal (Control + backtick) → Type codex.Now you see files created, preview documents, navigate visually.As Carl Says:“Open it in an IDE. Easiest way to see what it’s actually doing.”1b. The YOLO Mode HackCodex asks for permission constantly—every website, every command.Solution:codex --yoloFull access mode. No prompts. Just execution.“Haven’t broken my computer yet. We’re in this directory so it won’t leave.”1c. Codex vs Claude CodeSame task on both: Search web, summarize differences.Claude Code: 3 searches simultaneously, ~2 minCodex: One site at a time, asks permissions, ~4 minClaude Code is faster, hides details. Codex shows every command—more verbose.“It’s Apple versus Microsoft. Claude does things in a nicer interface. Codex shows you everything.”2. How to Handle Classic PM Tasks with CodexCodex shines at daily PM work.2a. File Analysis Without UploadingRun Codex from a folder, it accesses everything. No uploading.Carl has demo folder (Taskflow) with interviews, notes, PRDs.“What user interviews completed?” → Codex lists them“Top 3 pain points?” → Returns: voice input reliability, integration gaps, template workflowCreates document with direct quotes—no manual file providing.2b. Template-Driven WorkflowsSolution: Create /templates folder with markdown files.Example: Discussion Points, Action Items, Risks & Blockers, Next StepsUse: Summarize @meeting-notes using @templateSame format every time. Works for PRDs, one-pagers, research summaries.2c. Socratic Questioning for Better PRDsProblem: Asking Codex to write a PRD produces garbage without proper thinking.Solution: Socratic template makes Codex ask YOU questions first.Questions: “Why is this helpful? Data, feedback, or strategic?” “What must work for V1?” “Edge cases?”You answer. AI embeds your thinking.Then Codex reviews context, templates, example PRDs, and writes.Carl: “Goes from kind of there to a really good PRD almost right out of the box.”3. Advanced Codex Techniques for Future Vibe EngineersThis is where Codex separates from the browser.3a. Design Systems with StorybookVibe coder problem: “Make title pink” → wrong shade → 20 iterations → still jankyVibe engineer solution: Storybook (npm run storybook)See components visually, change colors instantly, see changes live without redeploying.Carl changes recipe title to pink: read-only mode to see plan, then YOLO mode to execute. Updates in Storybook immediately.Pre-built components: Use Shadcn UI for production-grade React components. Calendar, date picker, dropdown—all done.“All the logic and difficult things, you get for free.”3b. Test-Driven Development is The UnlockProblem: AI says “Done!” but it’s broken. AI will lie and set variables to true to pass tests.Solution: Write tests BEFORE building.Red-Green-Refactor: Tests fail → Build until pass → Improve codeCarl’s macro calculator:Tests: API returns calories, empty recipe returns null, missing data shows “N/A”, API fails retries 3x, divide by servings correctlyTold Codex: “Build to make tests pass.”35 minutes. Zero touch. All tests green. Feature worked.Carl: “If you write tests FIRST, they can’t cheat.”3c. An Example - The TikTok Recipe BotCarl built this for his girlfriend: TikTok recipe extractor.Problem: Recipe videos on TikTok. No written recipe. Just “comment and I’ll DM.”Solution: Paste URL → Codex downloads video → Sends to Gemini (only model that processes video) → Gemini extracts recipe → Codex formats to PDFHow: Detailed implementation spec: architecture, data flow, APIs, error handling, retry logic, tests.Gave to Codex in GPT-5 Codex mode. Left 35 minutes.Built entire feature. Tests passed. Worked first try.Carl: “First time I saw the dream—give it a medium-sized feature and it just builds it.”Where to Find Carl Vellotti* Linkedin* X (Twitter)* Instagram* NewsletterRelated ContentPodcasts:* Claude Code Tutorial* Windsurf Tutorial* AI Prototyping TutorialNewsletters:* Ultimate Guide to AI Prototyping Tools* AI Agents: The Ultimate Guide for PMs* How to Land a $300K+ AI Product Manager JobPS. Please subscribe on YouTube and follow on Apple & Spotify. It helps! This is a public episode. If you'd like to discuss this with other subscribers or get access to bonus episodes, visit www.news.aakashg.com/subscribe