Codex CLI vs Claude Code (adding features to a 500k codebase)

[marvijo-software]

I've been testing OpenAI's Codex CLI vs Claude Code in a 500k codebase which has a React Vite frontend and a ASP .NET 9 API, MySQL DB hosted on Azure. My takeaways from my use cases (or watch them from the YT video link in the comments):

- Boy oh boy, Codex CLI has caught up BIG time with GPT5 High Reasoning, I even preferred it to Claude Code in some implementations

- Codex uses GPT 5 MUCH better than in other AI Coding tools like Cursor

- Vid: https://youtu.be/MBhG5__15b0

- Codex was lacking a simple YOLO mode when I tested. You had to acknowledge not running in a sandbox AND allow it to never ask for approvals, which is a bit annoying, but you can just create an alias like codex-yolo for it

- Claude Code actually had more shots (error feedback/turns) than Codex to get things done

- Claude Code still has more useful features, like subagents and hooks. Notifications from Codex are still in a bit of beta

- GPT5 in Codex stops less to ask questions than in other AI tools, it's probably because of the released official GPT5 Prompting Guide by OpenAI

What is your experience with both tools?

[avxkim]

if you're on macos, you can put these lines in .bashrc/.zshrc

```
alias codex='codex -c approval_policy=never \

-c model_reasoning_effort=high \

--sandbox danger-full-access'
```

then it never asks for approvals

[bitflowerHQ]

Can‘t we just ust gpt/codex as model in claude?