</> aicodedetect

HTML & CSS AI Code Detector

Paste HTML markup, a CSS stylesheet or both to check whether a web page was likely written by an AI assistant or by a person. Free, instant, no sign-up.

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Signals that HTML and CSS were AI-generated

Markup has no algorithms to compare, so the evidence lives in structure, comments and the content itself. Generated pages tend to be complete, symmetrical and slightly generic.

  • Section-label comments. <!-- Hero Section -->, <!-- Features Section --> and <!-- Footer --> above every block, with matching comments in the stylesheet.
  • Semantic elements everywhere. header, nav, main, section, article and footer used exactly by the book, plus aria-label on elements that do not need one, in a beginner project.
  • The same CSS opening. A universal reset that zeroes margin and padding and sets box-sizing: border-box, then a :root block of custom properties for colours and spacing, then flexbox or grid for every layout.
  • Polish nobody asked for. transition: all 0.3s ease, hover effects on every card and button, soft box shadows and a single media query at a common breakpoint such as 768px.
  • Placeholder content. Generic company names, three feature cards with matching icons, invented testimonials and a copyright line, in a page that was meant to show one specific thing.

Why web pages are hard to attribute

Front-end courses teach the same reset, the same semantic layout and the same flexbox patterns, and templates from sites like CodePen or framework starter kits are copied constantly. A careful student can produce exactly the structure described above. HTML also carries less personal style than a programming language: there are only so many ways to write a navigation bar. That makes a result on a short fragment close to meaningless and a result on a full page only moderately informative.

Getting a useful answer

Paste the full page with its stylesheet, not a single component. Then compare the reasons with what you know: does the page match the brief, or does it contain sections and effects the assignment never mentioned? Does the author use the same class naming and layout approach in their other work? Asking someone to change the layout of one section in front of you settles most doubts quickly.

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Frequently asked questions

Which language should I choose for HTML or CSS?

Leave it on Auto-detect. HTML and CSS are not in the language menu, but the analysis recognises them from the snippet.

Can I paste HTML and CSS together?

Yes. A page with its style block, or an HTML file followed by its stylesheet, gives the analysis more to compare than either part alone.

Will a Bootstrap or Tailwind page look AI-generated?

Framework classes are shared by millions of sites, so they say little about authorship on their own. The analysis looks more at structure, comments and content than at which framework classes appear.

What about pages made with a website builder?

Builder output is machine-generated but not written by an AI assistant, and it often looks nothing like hand-written markup. A detector is not the right tool for it.

Is my code stored?

No. The snippet goes to a third-party AI model provider (Groq, with Google Gemini as a fallback) for the analysis and the result comes straight back to you. We do not save the code or write it to our logs.