AI innovation is going at warp speed, and keeping up is not easy. Being an early adopter gained a whole new meaning as trying anything just 1 week later means we are already behind. I recently spent the weekend testing the OpenAI Codex app and its coding models, and the experience felt much different from using the same models integrated in VSCode for example.
Until now, my AI usage in development was focused on code reviews or generating/refactoring code. Codex App goes further.
Rather than acting like simple (!! funny how we take amazing things for granted) autocomplete, Codex behaves more like an AI software dev assistant that can work across an entire codebase (or project as it is called under the Codex App).
The main difference is that Codex can operate in a sandbox environment where it can run commands, execute tests, and modify files before presenting results. It can also execute tasks outside that same sandbox, but by default, will request permissions to do so.
From what I’ve experienced, Codex App felt like a productivity boost when compared with the VSCode assistant. I’ve tried Copilot and Cline (Several models) in VScode and Claude as a separate assistant, and Codex App with ChatGPT5.4 and 5.3 Codex are up there as the best models I ve used.
Projects and Threads in Action
The way the Codex App is organized is with the concept of projects, where you define a repository or a folder with any kind of content inside. This project will create a sandbox environment on top of that codebase. Then you can create threads which are individual work streams that can work in parallel.
In one quick run, I had a basic recipe-management web app in under a minute. After a couple of iterations, I could already refine the structure, UI, and behavior. This was my prompt.
I need you to create a git repository where you will build the following. I have a list of favourite family recipes on my notes app. I want to create a local webapp that I can use to maintain those recipes.
This is phenomenal, in just a couple minutes I have a webapp to manage recipes with just one prompt. Obviously I can take this to another level with some more interactions and back and forward prompting.
Automations
Another very useful feature is the ability to create automations. You can simply create them with a prompt. For example, you can say:
Create a daily automation to clear pictures older than 7 days on my screenshot folder.
Another personal automation which I hope it will be useful 🙂
Notes
I showed here personal projects, but I also used it for work where it helped me specially with GIT, creating PRs and adhering to the requirements while doing so, Integrating with JIRA (via MCP) and fetching the related tickets to be included as part of the PR, that automation has been so far fantastic.
Codex won’t replace human judgment, but it does dramatically reduce the time between idea and implementation. It can act as a high-quality teammate for developers who want to build and iterate faster.
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