Where Claude tends to win
**Long, messy, real codebases.** Reading a site somebody else built, holding a lot of files in view at once, and making a change that does not break the other forty. This is the daily work of agency life and it is where we reach for Claude first.
**Following instructions it was given twenty steps ago.** Brand rules, spacing scales, a naming convention. Claude drifts less, which matters when the output has to look like it came from one team.
**Saying a thing is a bad idea.** It pushes back more readily, which is irritating for ten seconds and useful for the rest of the project.
Where the latest GPT tends to win
**Cold starts and breadth.** A blank file, an unfamiliar API, a format nobody in the room has used. The newest GPT models are excellent at getting something plausible on screen fast.
**Copy variants.** Fifteen headlines with an actual range between them, rather than fifteen rephrasings of the same sentence. For getting the words before the pixels this is a real tool.
**The ecosystem around it.** Images, voice, data, everything wired into one place. For a small team that matters more than a two-percent difference on a coding benchmark.
Where the difference is marketing
Both will write a responsive layout. Both will produce a form with validation. Both will confidently invent an API that does not exist, and both will do it in the same calm voice they use when they are right.
Neither knows which of your services is the profitable one. Neither knows that the last agency left a redirect map half finished. Neither will tell you that the page needs fewer sections, not more, because nothing in the request said so.
Choosing between them is a preference, roughly like choosing an editor. Choosing whether anyone reads the output is a decision with consequences.
How we actually run it
Exploration in whichever model is in front of us. Production work in the one that handles the codebase we are in. Every line read by the person whose name is on the invoice.
The models changed the ratio of our week: less typing, more deciding. The part clients pay for was always the deciding, so the work got better rather than cheaper, and the honest version of that sentence is that it also got faster.
If an agency tells you which model it uses as though that were the answer, ask instead who reviews the output. That is the question with money in it.
Questions we get asked
Which is better for coding, Claude or ChatGPT?
For working inside an existing codebase and holding instructions over a long session, Claude. For cold starts, breadth and copy variety, the newest GPT. The gap is small and it moves; neither replaces the review step that makes the output safe to ship.
Can I build a website with ChatGPT alone?
You can build a page. Turning it into a site means structure, speed, editability, redirects and analytics, and none of those are things the conversation reminds you about. That is the part where projects fail, and it is the same failure regardless of the model.
Does the model an agency uses matter?
Far less than their process. Ask who reads the generated code, what they delete, and what they test on a real phone before launch. An agency that answers those clearly is worth more than one with the fashionable model and no answer.