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Most "best AI for coding" comparisons benchmark the wrong thing. They ask each tool to write a function that reverses a string, note that all of them succeed, and declare a winner on style points.
Nobody's job is reversing strings. The job is a codebase you did not entirely write, with a bug that only appears in production, living somewhere in the interaction between four files.
The short answer
Claude for real projects — it reasons across many files better than anything else at this price, and Claude Code brings that into the terminal.
ChatGPT is a genuine competitor via Codex, and if you already pay for it, try that before adding another subscription.
Snippets and single functions
Tie. Genuinely.
Write a debounce function, parse this date format, give me a regex for postcodes — every current assistant handles these correctly. If this is your main use, pick on price or on whichever interface you prefer, because the code will be equivalent.
Real codebases
Claude wins.
This is where the tools separate. The task: here are twelve files, the checkout breaks when a discount code is applied to a basket containing a subscription item, find out why.
That requires holding the whole system in view — tracing what calls what, noticing that two modules make incompatible assumptions about the same data. Claude is consistently better at this. It is the difference between a tool that answers questions about code and one that reasons about a system.
It shows up most in refactoring. Ask for a change that touches eight files and Claude is more likely to notice the seventh and eighth.
Debugging
Claude, slightly.
Both are good with a stack trace. The difference appears on bugs without one — wrong output, no error, no obvious cause.
Claude is more inclined to say what it is uncertain about and suggest how to narrow it down. ChatGPT more often produces a confident single explanation, which is excellent when right and costs you an hour when wrong.
For debugging specifically, a tool that says "it is probably one of these three things, add a log here to find out" beats one that guesses decisively.
Terminal tools
Both now offer agents that work directly in your development environment rather than in a chat window: Claude Code and Codex.
This matters more than it sounds. Copy-pasting between a browser and an editor is where most of the friction in AI-assisted coding lives. A tool that reads your files, makes the edit and runs the tests removes that entirely.
Claude Code has been at this longer and is the more mature product. Codex is improving quickly. If you pay for either subscription already, the terminal tool is included — use it.
Verdict
| Task | Best pick | Notes |
|---|---|---|
| Snippets, single functions | Either | No meaningful difference |
| Multi-file reasoning | Claude | The clearest gap |
| Large refactors | Claude | Catches more of the knock-on changes |
| Debugging without a trace | Claude | Better at flagging uncertainty |
| Learning to code | ChatGPT | Gentler explanations, more material online |
| Code plus everything else | ChatGPT | One subscription, wider coverage |
A caveat worth stating: every one of these tools will confidently produce code that looks right and is wrong. Review what you merge. The productivity gain is real, and it evaporates the first time you ship a plausible-looking bug you did not read.