97 of 607 homepages ranked near 10,000 in Tranco are invisible without JavaScript

Allowing an AI crawler in robots.txt only answers permission. It says nothing about whether the crawler can actually read anything once it arrives. Most AI crawlers, including the ones that feed ChatGPT and Perplexity citations, do not execute JavaScript. If a page's content only exists after the browser runs a script, a crawler that respects robots.txt and is fully welcomed still sees a near-empty shell.

On 2026-08-31 I fetched the homepage of 607 sites once, with no JavaScript executed, scripts and styles stripped, and measured the visible text that survived. 481 (79.2%) had substantial readable text. 97 (16.0%) were effectively empty, under 250 characters. Another 29 (4.8%) were thin, under 800 characters - enough to exist, not enough for an answer engine to summarize confidently. 58.0% of the 607 carried no JSON-LD structured data and 26.4% had no meta description, so even some of the readable pages give a crawler little to cite from.

This is a separate, smaller check from the flagship 5,000-site robots.txt census: 900 sites attempted, 607 fetched, ranked roughly 10,000 to 10,700 in the Tranco list rather than the top 5,000. It measures a different, harder problem than robots.txt. A blocked crawler is a one-line fix. A page that only renders after hydration needs real engineering - server-side rendering, static generation, or at minimum enough text in the initial HTML for an answer engine to work with.

The table below lists every invisible and thin homepage from this run, in rank order. A rank near 10,000 in a research list that averages several traffic sources still means real, visited sites - this is not an edge case confined to obscure domains.

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Enter your domain and email. One email if we find your site is rendering blank to non-JS crawlers, or if that changes. No spam.

The 60 most affected sites by rank from this run - the full aggregate is in the open dataset under rendering_census.