GPT 5.3-Codex & Codex APP: I Built My AI Mission Control (ChatGPT + Claude + Gemini in One Dashboard)
How I Used OpenAI’s Free Codex App to Build a Multi-Model AI Chatbot Manager, Using Gemini, ChatGPT, and Claude in One App.
Want to build apps using AI coding agents?
You need a $20/month Pro subscription.
No Pro account = No access to AI coding agents.
OpenAI just solved this problem.
They released the Codex App with GPT 5.3-Codex inside.
Free. No subscription. 1M+ users now testing.
Today, we’ll build a full-stack AI Chatbot Manager.
But first, let’s cover the fundamentals.
What is GPT 5.3-Codex?
OpenAI launched it in February 2026.
It can build entire apps.
It’s 25% faster than before.
OpenAI also released an app; let’s discover it too.
What is Codex App?
OpenAI’s new app for GPT Codex models.
It has 3 features:
New thread: You can run more than one task at the same time.
Automations: Set automation, and these agents do tasks for you, like
Scan recent commits
Skills: Using preset skills, you can build agents, apps, and better frontends.
Using the OpenAI Codex App, we’ll build an AI Chatbot Manager.
AI Chatbot Manager - Simple Overview
The Problem is paying $60/month for ChatGPT Plus, Claude Pro, and Gemini Advanced separately.
Our solution is building a single app with a single prompt.
It connects to all three major LLM services using their APIs for a fraction of the cost.
So, you can use all major AI models by adding their API’s, and see the cost at the same time.(ChatGPT, Claude, Gemini.)
Fast-forward to what it looks like
Let’s check the app we’ll build in this one.
Building With Codex
Now it is time to build.
Let’s build something meaningful.
To do that, I headed to the vault.
Let’s check “Personal AI Chatbot Manager”, prompt, and copy it.
There are 70 Claude Code prompts here, for you to build, btw.
It started building.
This is the best part.
It is building, I opened a movie and keep building while watching.
Before discovering all of the Codex features, let me remind you that LearnAIWithMe paid perks.
LearnAIWithMe Paid Perks
The standard subscription ($12/mo or $100/year) gives you full access to all my articles and posts on Substack
The Founding Member tier ($200/year) includes everything above PLUS access to The Vault, 800+ prompts, projects, AI tools, and AI labs.