What GTmetrix does
GTmetrix is a page performance testing service that fetches pages when a user runs a speed test. Its default user agent is a standard Chrome on Linux string with a trailing "GTmetrix" tag, which is the identifying feature in server logs. The service is on Cloudflare's verified bots list so its tests can pass spam protection, and users can optionally anonymize the user agent (removing the tag) or, on PRO plans, override it entirely to emulate specific devices.
How to control GTmetrix
Target GTmetrix in your robots.txt with the GTmetrix token. Rules apply per bot, so you can allow this one while blocking others, or the reverse.
Allow GTmetrix
User-agent: GTmetrix
Allow: /Block GTmetrix
User-agent: GTmetrix
Disallow: /GTmetrix is on Cloudflare's verified bots list, but users can anonymize or override the user agent, so the "GTmetrix" tag is not guaranteed to appear on every test request.
How to identify GTmetrix
Temso identifies GTmetrixtraffic by matching the request's User-Agent header against this pattern. User-agent strings can be spoofed, so treat a match as an indication, not proof.
GTmetrixGTmetrix FAQ
What is GTmetrix?
GTmetrix is a website speed testing service that loads pages on request to measure their performance. Its requests carry a normal Chrome user agent string ending in a "GTmetrix" tag, and it is listed on Cloudflare's verified bots list.
How do I block GTmetrix?
You can add a robots.txt group with "User-agent: GTmetrix" and "Disallow: /", and some sites block it by detecting the "GTmetrix" tag in the user agent and returning a 403. Note that requests are triggered by users running tests, and GTmetrix offers an "Anonymize User-Agent" option and a PRO user-agent override that remove the tag, so user-agent based blocking is not fully reliable.
About SEO & Analytics Crawlers
Crawlers behind SEO and marketing-intelligence platforms: backlink databases, site audits, rank tracking, and brand monitoring.
Blocking these has no effect on search or AI visibility. It mainly limits what third-party tools (including your competitors' tools) can see about your site.
