👀 For a few weeks I worked closely with both - and the answer to "which is better" turned out to be unexpected. Spoiler: I choose to use them together. Now to the details
My personal take on Codex and Claude:
Codex writes code well - and checks code written by others even better. It's especially sharp at tearing apart what Claude wrote: finds weak spots, points out architectural mistakes, suggests alternatives. Claude is different: strong at planning, great at building architecture, sees the whole system on the first try. In code quality they're roughly equal - but there's one fundamental difference that changes the whole pipeline
The main gap - the context window:
📌 Claude Opus 4.7 - 1 million tokens, holds the entire codebase in memory at once
📌 Codex ChatGPT 5.5 - a context window 4 times smaller‼️, but it focuses well on a specific chunk
📌 The upshot - Claude handles systems thinking, Codex - pinpoint analysis
That's exactly why they're not competitors - they're complementary tools with different strengths
How I split the roles between them:
⚡️ Claude - planning, writing the architecture, first-pass code
⚡️ Codex - fact-checking what's been written, critiquing decisions, final approval
⚡️ The combo - always together, never solo
This isn't about convenience - it's a qualitatively different result. Claude with its 1M tokens keeps the whole project in its head and writes code in the context of the entire system. Then Codex looks at a specific module with fresh eyes and finds what Claude might have missed precisely because it saw too much. I got this after the very first joint session - two tools gave a better result than each one on its own
And this is only the beginning. Ahead are big multi-level architectural systems where every stage has its own model plugged in. One is in charge of architecture - like Claude now. Another checks and critiques the code - like Codex. A third generates images. A fourth conducts the agents. Not one universal model - a whole orchestra of specialized ones. And the sooner you start thinking this way - the faster you'll get to systems that really work above the level of an average developer
💻 In practice a multi-model pipeline is cheaper and better than one model for every task
⭐️ Andrej Karpathy, former Director of AI at Tesla, OpenAI co-founder:
"The hottest new programming language is English"
🎯 "Claude or Codex?" is the wrong question. The right one: when Claude, when Codex, and how they complement each other. It's like a phone with several SIM cards: whatever country you travel to - the right one switches on by itself