The best AI model for building a website depends on your budget. Here's how to run a test on your own, what to compare, and how to weigh cost against quality.
GeneralOctober 10, 20267 min read
The best AI model for building websites is the one that builds your site correctly in the fewest instructions at a cost you're comfortable with, and the only reliable way to find it is to give two or three models the same brief and compare what they produce. Coding leaderboards measure general ability on someone else's tasks. They can't tell you which model will follow your brief, respect your facts, and write code you can maintain.
Model lineups also change often, so any "best model" list is out of date soon after it's written. This guide skips the list and gives you a test you can rerun whenever the lineup changes, using Carpathian App Builder, where you pick the model for every instruction and see each one's cost as it works.
Why can't a leaderboard answer this?
A benchmark scores a model on a fixed set of problems, usually small, self-contained coding tasks with a right answer. Building a website is a different job. It's a long run of decisions, most of which have no single right answer, judged against a brief only you have read.
What makes a model good at your website:
Following the brief. Does it build the pages you asked for, with your content, and nothing you didn't ask for?
Respecting your facts. Does it use your prices and copy, or improve on them with inventions?
Code you can keep. Is the structure clear enough that you, a developer, or another model can change it later?
Taking direction. When you ask for one change, does it make one change?
A model can score well on benchmarks and still pad your site with invented testimonials. You'll only find that out by looking.
How do you run a fair comparison?
Give each model the same brief, the same reference documents, and the same first instruction, in separate apps, then compare the results side by side. Keep everything else fixed. If one model gets a better prompt, you're testing your prompt, not the model.
In App Builder, the steps are:
Write your brief and upload it, along with any data files, as reference documents.
Create one app per model you want to test, for example "Bakery site, model A" and "Bakery site, model B," and upload the same documents to each.
Give each app the identical first instruction, with a different model selected in each.
Once they finish, give each app the same two or three follow-up instructions, the kind of changes you'd make on any site.
Compare the previews, the files, the diffs, and the costs.
You can also select several models on one instruction in a single app. That starts one agent per model, all working at the same time, each with its own progress, tokens, and cost shown in the Agents tab. It's a quick way to see how differently models plan and how much each spends. Those agents share one set of files, though, so for comparing finished sites, separate apps keep each model's work apart.
Compare what a visitor would see, what a developer would inherit, and what it cost. A site that looks right in the preview but invented half its content fails the first test. A site that's correct but built as one enormous file fails the second, the first time you need to change it.
Go through each result with this list:
The preview. Does every page you asked for exist and look the way the brief describes? Open the Preview tab and click through all of it, then check how it looks at a phone width.
The facts. Check every price, name, date, and claim against your documents. Count the inventions.
The file structure. Open the Files tab. Look for sensible names, styles and scripts kept in their own files, and nothing duplicated across pages that should be shared.
The README. Does it explain how to run the project and which environment variables it needs?
The follow-ups. Read each follow-up's diff in the Changes tab. A good model changes what you asked for and leaves the rest alone. A diff that touches files unrelated to the request is a warning.
Accessibility basics. Alt text on images, headings in order, readable contrast, and labels on form fields.
The cost. The Agents tab shows each agent's tokens and cost, and the app's total for the month.
Write down what you find for each. After two or three models, the differences are usually obvious, and they're rarely the differences you'd have guessed.
Should you pay more for a stronger model?
Sometimes. A stronger model costs more per token, but it may finish in one pass what a smaller model needs several follow-ups to get right, and each of those follow-ups costs tokens too. Compare the total cost to reach a site you'd publish, not the per-token rate.
App Builder shows each model's rate beside it in the model picker, and the Agents tab shows what each run spent, so you can work this out from your own test instead of estimating:
Add up the cost of the first instruction and every follow-up it took to reach a finished site.
Count your own time too. Every round of correcting a cheaper model is time you spend reading diffs.
Note which model needed the fewest corrections to its facts. Those are the mistakes that are costly to miss.
For a simple site, the answer is often that a smaller model is enough. A one-page landing page or a brochure site with a few pages is well within what smaller models handle. Larger models earn their rate on longer jobs: sites with many pages that share components, apps with their own logic, or a large existing codebase that has to be read before it can be changed.
When should you rerun the test?
Rerun it when the model lineup changes, when your project changes shape, or when the model you're using starts needing more corrections than it used to. An old test tells you little about models released since you ran it.
A few triggers:
A new model appears in the picker. Run your saved brief through it once.
Your site grows from a few static pages into something with logic, forms, or data. The model that was fine for the brochure site may not be the right one now.
You notice your follow-ups are mostly corrections. That's the model telling you it's out of its depth on this project.
Keep your brief and reference documents from the first test. Rerunning it then takes one new app and one instruction.
Does the model change the code you end up owning?
Yes, and that's a reason to look at the files and not only the preview. Two models given the same brief will structure a site differently, name things differently, and make different choices about what goes where. Whichever result you keep becomes the codebase every later change is built on, by a model or by a person.
Whatever you pick, the result is ordinary source code. You can download any app as a zip, and nothing in it ties you to the model that wrote it. You can switch models between instructions on the same app, so a stronger model can lay the foundation and a cheaper one can handle the small changes after it.
Where Carpathian fits
App Builder lets you choose a model for every instruction, see each model's per-token rate before you start, run several agents at once, and read each agent's tokens and cost as it works. Every run is billed as AI usage at the chosen model's rates, the same as the rest of Carpathian AI, and current rates are on the AI model pricing page.
The lineup is the set of models Carpathian offers that can call tools, not every model in existence. If your team has standardized on a model App Builder doesn't offer, this isn't the tool for that. App Builder also writes and previews code without hosting it, so the finished site goes on the host of your choice.
Create an account and enable App Builder from Services, or contact us if you want help choosing a model for a larger project.
Which AI Model Is Best for Building Websites? | Carpathain | Carpathian
