If you've Googled this, you've probably already used both and still aren't sure which one to trust with your actual codebase. Here's my concrete answer after running both through real code review workflows: they're good at different things, and picking the wrong one for the job costs you time. Here's exactly how to choose.
ChatGPT (GPT-4o) is faster and more conversational. It's excellent at quick back-and-forth — paste a function, ask a question, iterate. Claude (Sonnet or Opus) handles larger context windows more gracefully and tends to produce more structured, thorough analysis when you give it a full file or a diff.
That's not a vibe — it's a practical difference. On a recent project, I fed both models the same 400-line service file and asked for a review. ChatGPT flagged the most obvious issues quickly. Claude caught a subtle state mutation buried in a helper that was three function calls deep. Both missed things. But they missed different things.
For any non-trivial code review, I use this with Claude:
Review the following code as a senior engineer doing a pull request review.
Structure your response as:
1. Critical issues (bugs, security, data integrity)
2. Design concerns (architecture, coupling, testability)
3. Minor improvements (naming, style, readability)
4. Questions I should answer before merging
Be specific. Reference line numbers or function names. Skip praise.
[paste code here]
The "skip praise" instruction is load-bearing — without it, both models pad their output with positive framing that buries the real findings.
Stop treating this as a permanent either/or. Use ChatGPT for fast conversational review of small pieces. Use Claude when you're doing a serious pre-merge review of a whole module. The engineers who get the most out of AI code review aren't loyal to one model — they know which tool fits which context.
The instinct to pick a winner and stick with it is the same instinct that leads people to use a screwdriver as a hammer. Both tools exist. Use them correctly.
I break down one workflow like this every week in The AI Leverage Weekly — practical, no fluff, free. Subscribe: https://theaileverageweekly.beehiiv.com/subscribe?utm_source=devto&utm_medium=article&utm_campaign=medium_w6