Pre-rendering Tester
Free tool · User agent comparison
Pre-rendering tester
Requests the same address as a normal browser, as Googlebot, and as GPTBot, and compares what comes back. If your setup serves bots something different, this shows you what and how much.
What Is This Pre-Rendering Tester?
This tool checks whether your page serves the same content to a normal browser, Googlebot, and GPTBot, or whether one of them gets something different.
It requests the same address three times, once per user agent, and compares the status code, title, H1, meta robots, X-Robots-Tag, word count, and byte size returned each time. It does not execute JavaScript, so it cannot show you a rendered, post-JavaScript version of the page.
What This Tool Checks
- Response status: Compares the HTTP status code returned to each of the three user agents.
- Title and H1: Compares the page title and first heading returned to each user agent.
- Meta robots and X-Robots-Tag: Compares indexing directives returned to each user agent.
- Word count and byte size: Flags a difference in word count greater than about 5%, or any difference in byte size, as a likely content difference.
- Cloaking signal: Flags whether all three user agents receive the same page, or whether one is served something different.
What This Tool Does Not Check
- Does not execute JavaScript or show a rendered version of the page; it compares served HTML only
- Does not tell you whether your content depends on client-side rendering; if it does, every user agent here will look equally thin
- Does not guarantee that search engines will index your page
- Does not guarantee AI crawler visibility
- Does not measure Core Web Vitals or page speed
- Does not automatically fix serving or cloaking issues
Why Check This?
If a server treats Googlebot, GPTBot, or other crawlers differently from a normal browser, whether intentionally or through a caching or bot-management misconfiguration, that's a form of cloaking that can affect how a page is crawled, indexed, or cited.
Comparing what each user agent actually receives helps you catch an unintended difference before it affects how your content is found.
How to Test Your Page
- Enter the address you want to compare.
- Run the check. The tool requests that one address three times, a second or two apart, once as a normal browser, once as Googlebot, once as GPTBot.
- Review the table: status, title, H1, meta robots, X-Robots-Tag, word count, and byte size for each of the three.
- If a difference shows up, check whether it's intentional (for example, a caching layer or bot-management rule) or an unintended cloaking issue to fix.
- If the page looks thin to all three user agents equally, that points to a JavaScript-rendering issue instead, which needs a different tool that reads raw HTML.
Frequently Asked Questions
What is this Pre-Rendering Tester actually checking?
It checks whether a normal browser, Googlebot, and GPTBot are served the same version of a page. It compares served HTML across the three user agents; it does not execute JavaScript.
Does this tool compare initial HTML with a JavaScript-rendered version?
No. It never runs JavaScript, so it cannot show a rendered version of the page. All three requests it makes return the raw served HTML only.
Why would a page serve different content to different user agents?
This can happen intentionally, such as serving a cached or simplified version to crawlers, or unintentionally, through a misconfigured caching layer or bot-management rule. Either way, comparing the three helps you spot it.
My page looks the same for all three user agents, does that mean it's not JavaScript-dependent?
Not necessarily. If the page relies heavily on client-side rendering, all three user agents here would receive the same thin HTML, since none of them run JavaScript. This tool only flags differences between the user agents, not JavaScript dependency itself.
Which user agents does this tool use?
A standard desktop Chrome browser, Googlebot, and GPTBot.