Fetch & Render Simulator
Tool designed to simulate the googlebot fetch & render. Will return
rendered, and initial source code (obeys the user-agent specified) and a
screenshot at desktop resolution & mobile resolution.
Optionally you can also run a lighthouse test as well. Although intended to match, parity with the Google WRS cannot be guaranteed, always confirm in either the Mobile-Friendly Test or URL Inspection tool in Search Console.
Honour robots.txt uses the google open source parser, robots.txt files are fetched fresh for each test.
Test results deleted after 5 mins max, tests are not logged.
URL is required
Flattening the DOM will pierce the Shadow DOM, and also render
content of iframes
Overlay / Output Core Web Vitals will show LCP element, any LCP Shift & FID (basically runs this bookmarklet you can run in you browser) details will appear in a panel under the HTML.
User Agent / Referrer
Uses these excellent open source projects:
for robots.txt parsing and matching &
for DOM flattening.
iframe flattening inspired by a discussion with Glenn Gabe ( @glenngabe ), of G-Squared Interactive