Overview of prerender crawlers

User Agent

Prerender crawler User-Agent will always contain: 

Prerender (+https://github.com/prerender/prerender)
Crawler Full user agent string
Prerender desktop
Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) HeadlessChrome/W.X.Y.Z Safari/537.36 Prerender (+https://github.com/prerender/prerender)
Prerender mobile
Mozilla/5.0 (Linux; Android 11; Pixel 2 XL) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/W.X.Y.Z Mobile Safari/537.36 (compatible; Googlebot/2.1; +http://www.google.com/bot.html) Prerender (+https://github.com/prerender/prerender)
Prerender sitemap worker
Prerender (+https://github.com/prerender/prerender)

Wherever you see the string Chrome/W.X.Y.Z in the user agent strings in the table, W.X.Y.Z is a placeholder that represents the version of the Chrome browser used by that user agent: for example, 89.0.4389.82.

These values can be spoofed. If you need to verify that the visitor is Prerender, you should use reverse DNS lookup.

Prerender crawler IP address ranges

To verify that Prerender is the crawler:
Run a reverse DNS lookup on the accessing IP address from your logs, using the host command. Verify that the domain name is prerender.io. Run a forward DNS lookup on the domain name retrieved in step 1 using the host command on the retrieved domain name. Verify that it's the same as the original accessing IP address from your logs.
> host domain name pointer us-mci1-38.renders.prerender.io.

> host us-mci1-38.renders.prerender.io
us-mci1-38.renders.prerender.io has address
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