What is Prerender?
Prerender renders JavaScript-heavy pages into static HTML on behalf of site owners, helping search engines, AI crawlers, and social platforms access their content. You can set up Agent Analytics to see when Prerender visits your website.
Overview
| Operated By | Prerender |
| Source | Official Website |
| Expected To Follow Robots.txt | No |
| Insights Last Updated | September 14, 2026 |
Do you operate this agent? Contact us to suggest an update.
Category
Expected Behavior
Prerender renders a site's JavaScript pages into static HTML for search, AI, and social crawlers. It fetches pages queued by the site owner's Prerender.io integration or cache settings rather than crawling for its own purposes.
Prerender's User Agent
| User Agent | Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) HeadlessChrome/99.0.4844.84 Safari/537.36 Prerender (+https://github.com/prerender/prerender) |
How To Block Prerender With Robots.txt
Add this rule to your robots.txt file to request that Prerender not access your website, or use Automatic Robots.txt to request the same of all developer helpers at once. You can customize which pages are blocked by swapping out / for a different path.
User-agent: Prerender # https://knownagents.com/agents/prerender
Disallow: /Insights for Prerender
As of September 14, 2026, this data reflects agent visits measured across thousands of websites using Agent Analytics, combined with daily scans of the top 1000 websites and their robots.txt files.
Robots.txt Blocked Percentage
Country of Origin
Robots.txt Blocking Trend
6% of top websites block Prerender in their robots.txts.
Overall Developer Helper Traffic
0.8% of all web traffic came from developer helpers.
Frequently Asked Questions
Should I Block Prerender?
Usually no if your organization uses Prerender.io, because blocking Prerender stops pages from being rendered or refreshed. Exclude unwanted URLs through your integration or Prerender.io's cache rules instead. For context, 6% of the top websites we track currently have robots.txt rules for Prerender.
Does Prerender Follow Robots.txt Rules?
Not directly. Prerender.io says its renderer does not read robots.txt. Your integration determines which URLs it receives. Use integration filters or Prerender.io's ignored URL rules to exclude pages.
Does Prerender Access Private Content?
No. Prerender.io receives URLs without cookies or authentication headers, so it sees only content available to an unauthenticated visitor.
How Can I Tell if Prerender Is Visiting My Website?
Agent Analytics tracks Prerender visits. Compare the requested URLs with your Prerender.io Cache Manager, and use reverse DNS or IP verification because user-agent strings can be spoofed.
Why Is Prerender Visiting My Website?
Prerender is rendering a URL queued by your Prerender.io integration, sitemap, cache settings, dashboard, or API.