ChatGPT 5.5 Codex is the greatest AI coding tool ever. Here's how to use it
TL;DR
Alex Finn says Codex beats Claude Code right now — his case is a mix of product quality and economics: ChatGPT Codex is included on the free tier, works well at $20/month, and offers far higher practical usage than Anthropic’s current limits.
His signature workflow is parallel agents, not one giant prompt — in one session he has Codex building a stock investing app, a second agent making a launch video with Remotion, and a third using computer use to research AI stocks like Nvidia, Microsoft, Broadcom, TSMC, and ASML.
The killer differentiator is integrated image generation for UI design — before writing code, he prompts Codex to create five stock-app interface concepts, picks a dark-mode portfolio-focused layout, and uses that image as the blueprint for the app.
Codex’s in-app browser and annotation loop make editing feel unusually tight — he highlights a spot in the live preview, asks for a dark mode toggle, and the app adds it immediately, which he frames as something no other “vibe coding” tool currently matches.
He pushes a full-stack build, not just a flashy front end — the demo wires a Convex database for persistent portfolio storage and Alpha Vantage for live stock prices, then lets him add holdings like ASML with share counts and real-time value tracking.
The Remotion skill turns the app into launch-ready marketing assets — Codex generates a 40-second promo video using the app’s real UI, which Finn says previously would have cost “tens of thousands of dollars” and days of agency-style work.
The Breakdown
Why Finn Thinks Codex Is the New Default
Alex Finn opens at full volume: he’s “absolutely in love” with ChatGPT 5.5 Codex and thinks it’s the best AI coding tool on earth right now, even ahead of Claude Code. His argument is practical, not abstract — Codex is available on the free tier, still compelling at $20/month, and doesn’t make him sweat usage caps the way Anthropic does.
Starting with UI, Not Code
Instead of jumping into scaffolding, he starts by designing the app visually with OpenAI’s integrated image generation. He prompts Codex to create five stock investing app concepts — charts, research, news, portfolio — then picks the version that best emphasizes saved holdings, saying that designing first leads to dramatically better front ends.
Turning a Mockup into a Full-Stack App
Once he picks the winning interface, he tells Codex to build it and connect a Convex database so the portfolio persists. He pauses to make a broader point in his usual “make tons of money” voice: if you’re serious about real apps or businesses, you need the whole stack, and Convex is his favorite because he’s built roughly 50 apps on its free tier without paying.
The Core Workflow: Multiple Agents All the Time
This is where the video’s real thesis kicks in: don’t use Codex as one chatbot, use it like a swarm. While the main agent builds the app, he opens another chat to use the Remotion skill for a launch video, and another with computer use to open Chrome and research “the best AI stocks to invest in 2026.” He compares it to StarCraft: send out your zerglings, keep multiple fronts moving, and approve work as it comes back.
Live Editing Inside the Browser
When the initial app preview appears, Finn is visibly impressed that it looks almost exactly like the chosen mockup. Then he shows his favorite trick: using the built-in browser’s annotation tool to click directly on the UI and ask for a dark mode button, which Codex adds and tests on the spot.
Reverse Prompting and Adding Real Data
Even though he already knows he wants live market data, he stops and asks Codex what should come next — something he calls “reverse prompting” and says people should do 10x more often. Codex suggests real search, chart data, portfolio upgrades, and research; he chooses live stock data first, lands on Alpha Vantage, and wires in real prices that match Robinhood for Google and Nvidia.
Marketing Video, Persistent Portfolio, and Trusting the Tool
The Remotion agent finishes with a polished 40-second launch video built from the app’s actual UI, and Finn reacts like he just watched an agency compress into software. Back in the product, he prompts for a real portfolio flow, adds ASML with 100 shares, and shows the position storing to Convex with live valuation. By the end, he’s advocating full-access mode, medium reasoning for most tasks, and ongoing automations like code-quality checks against GitHub — basically, let Codex keep working while you keep steering.