Make Your Structured Data Accessible

A recent investigation revealed a problem for websites that rely on JavaScript for structured data.

That data, often in JSON-LD format, is difficult for AI crawlers to access if it’s not in the initial HTML response.

Crawlers such as GPTBot (which uses ChatGPT), ClaudeBot, and PerplexityBot cannot execute JavaScript and miss structured data added later.

This creates challenges for websites that use tools such as Google Tag Manager (GTM) to inject client-side JSON-LD, as many AI crawlers cannot read dynamically generated content.

Key findings about JSON-LD & AI indexing tools

Elie Berreby, founder of SEM King, tested what happens when JSON-LD is added using Google Tag Manager (GTM) without server-side rendering (SSR).

He revealed why AI indexing tools often don’t see this kind of structured data:

1. Initial HTML loading: When a crawler requests a web page, the server returns the first HTML version. If structured data is added with JavaScript, it will not be in this initial response.
2. Client-side JavaScript execution: JavaScript runs in the browser and modifies the Document Object Model (DOM) for users. At this stage GTM can add JSON-LD to the DOM.
3. Crawlers without JavaScript rendering: AI crawlers that cannot run JavaScript cannot see changes to the DOM. This means they are missing the JSON-LD added after the page is loaded.

In short, structured data added only via client-side JavaScript is invisible to most AI crawlers.

Why traditional search engines are different

Traditional search crawlers such as Googlebot can read JavaScript and process changes made to a web page after it is loaded, including JSON-LD data injected by Google Tag Manager (GTM).

In contrast, many AI crawlers cannot read JavaScript and only see raw HTML from the server. As a result, they miss dynamically added content, such as JSON-LD.

Google warning about excessive use of JavaScript

This challenge is connected to a wider one Google warning about excessive use of JavaScript.

In a recent podcast, Google’s search relations team discussed the growing reliance on JavaScript. While it allows for dynamic features, it’s not always ideal for essential SEO elements like structured data.

Martin Splitt, Google’s search developer representative, explained that websites range from simple pages to complex applications. It is important to balance the use of JavaScript and make key content available in the initial HTML.

John Mueller, another proponent of Google Search, agreed, noting that developers often turn to JavaScript when simpler options, like static HTML, would be more effective.

What to do instead

Developers and SEO experts should ensure that structured data is available to all crawlers to avoid problems with AI crawlers.

Here are some key strategies:

1. Server Side Rendering (SSR): Display pages on the server to include structured data in the initial HTML response.
2. Static HTML: Use schema markup directly in HTML to limit reliance on JavaScript.
3. Prerendering: Offer pre-rendered pages with JavaScript already executed, giving crawlers fully rendered HTML.

These approaches align with Google’s advice to prioritize HTML-first development and include important content such as structured data in the initial server response.

Why this is important

AI indexing tools will only grow in importance, and they play by different rules than traditional search engines.

If your site depends on GTM or other client-side JavaScript for structured data, you’re missing out on opportunities to rank in AI-driven search results.

By moving to server-side or static solutions, you can future-proof your website and ensure visibility in traditional and AI searches.

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