JS SEO DEV

Do AI crawlers like GPTBot and ClaudeBot run JavaScript? JS SEO Lab measures it instead of repeating opinions.

Since May 2026 I've been running a public lab: 55 test pages that put content on the page in eight different ways (plain HTML, images added by JavaScript, content behind a click, loaded from an API, or only on scroll) across five page types. A tracker on my own server logs every bot that visits. For each visit I check three things: who came, whether it actually ran the page's JavaScript, and whether the bot is who it claims to be.

On this channel: what GPTBot, ClaudeBot, Meta-ExternalAgent, Bingbot and other crawlers really do with JavaScript. One dated finding at a time, limits stated, corrections made in public.

Findings and the live dashboard: https://jsseo.dev

I'm Jakub Sawa, a technical SEO consultant with 25+ years in the field. The lab feeds my audit work, so results that suit me get checked harder, not softer: https://jakubsawa.pl