Prerender is a bot in the SEO crawlers category, operated by Prerender, LLC.
It's HTML pre rendering service for SPA(Single Page Application) Website SEO.
SEO crawlers map links, keywords and technical issues for SEO tools and backlink databases. They help the tool's customers, often your competitors, rather than you. Rate limit or block the ones you do not use.
Prerender identifies itself with this user agent string:
PrerenderAnyone can copy a user agent string. Transfon Security also checks where each request comes from, so a request that claims to be a known crawler but comes from the wrong network is treated as a fake, not as the real crawler.
We have not confirmed whether Prerender follows robots.txt. Add a rule, then check your logs to see that it stopped. robots.txt is a plain text file at the root of your domain, such as https://example.com/robots.txt.
User-agent: Prerender Disallow: /
User-agent: Prerender Disallow: /private/ Disallow: /search
User-agent: Prerender Allow: /blog/ Disallow: /
User-agent: Prerender Allow: / User-agent: * Disallow: /
User-agent: Prerender group, Prerender ignores your User-agent: * rules, so repeat any that should still apply.Prerender from Prerender's user agent; check Prerender, LLC's own documentation if it publishes a different robots.txt name.Treat robots.txt as a statement of your policy, and enforce it where requests arrive.
Prerender works for an SEO tool's customers, often your competitors. It adds server load without readers, so rate limit or block it unless you use the tool.
Transfon Security for publishersSEO crawlers map landing pages and links for competitor research. Keep Prerender's visits out of campaign data.
Transfon Security for advertisersPrerender can map your catalogue, prices and site structure for competitors. Block it unless you use the tool yourself.
Transfon Security for e-commerceAllow Prerender only if your team uses the tool; otherwise rate limit it on docs and marketing pages.
Transfon Security for SaaS and APIsrobots.txt is a request, not an enforcement. Transfon Security shows Prerender by name in the Top Bots report, so you can see how often it visits and which pages it reads. Block or allow it with a User Agent rule, or slow it down with a rate limit decision rule.
Transfon Security
Prerender is a bot in the SEO crawlers category, operated by Prerender, LLC. It's HTML pre rendering service for SPA(Single Page Application) Website SEO.
We have not confirmed whether Prerender follows robots.txt. Add a robots.txt rule, then check your logs to see that it stopped, and block it by user agent if it did not.
Add "User-agent: Prerender" followed by "Disallow: /" to the robots.txt file at the root of your site. To enforce it, block requests whose user agent contains "Prerender" at your WAF. In Transfon Security that is one User Agent block rule.
No. robots.txt is voluntary, so Prerender may not follow it, and anyone can send Prerender's user agent, so a fake Prerender ignores your rule. Enforce the rule where requests arrive, at your WAF, and check the source network.
SEO crawlers map links, keywords and technical issues for SEO tools and backlink databases. They help the tool's customers, often your competitors, rather than you. Rate limit or block the ones you do not use.
Transfon Security identifies every bot in this directory in your traffic reports, flags fake search crawlers, and lets you allow, block or rate limit each bot.
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