How do I stop Prerender from caching certain URLs?

TL;DR

Prerender caches every URL a crawler requests by default, including variations caused by tracking parameters like utm_source and fbclid. You can control this in three ways: ignore specific query parameters to eliminate duplicate cache entries, set URL pattern rules to return a 404 for matched URLs, or adjust your integration to filter requests before they reach Prerender. For most sites, ignoring tracking parameters is the quickest win — it requires no code changes and reduces render usage immediately.

Ignore query parameters to reduce duplicate cache entries

When Prerender receives a URL with a parameter set to ignore, it strips that parameter and serves the cached version of the base URL instead.

For example, if utm_source is set to be ignored and Prerender receives:

https://example.com/path?utm_source=newsletter&utm_medium=email

It strips the parameter and serves:

https://example.com/path

This means Prerender caches one page instead of a separate entry for every parameter variation.

Default ignored parameters

Every account registered after January 2022 has the following parameters configured to be ignored by default:

Parameter	Commonly used by
`utm_medium`	Google Analytics
`utm_source`	Google Analytics
`utm_campaign`	Google Ads
`utm_content`	Google Ads
`utm_term`	Google Analytics
`gclid`	Google Ads
`fbclid`	Facebook / Pixel

ℹ️ If your account was created before January 2022, these parameters are not set up by default. Add them manually using the steps below.

You can also configure Prerender to ignore all query parameters, or to only cache specific query parameters and ignore the rest. Both options are available in Cache Manager > Caching Rules.

Add a URL parameter ignore rule

⚠️ Adding a new ignore rule does not automatically remove existing cached URLs that already contain that parameter. After adding the rule, clear your cache manually from your dashboard to remove those entries.

In your Prerender dashboard, go to Cache Manager and click Caching Rules at the top.
Click Add Parameter.

Enter the parameter name you want to ignore.

ℹ️ Wildcard patterns are supported. For example, fb* matches fb_action_ids and any other parameter beginning with fb. The dashboard shows how many of your cached URLs are affected by the pattern before you save.

Verify the new parameter appears in the list.

ℹ️ Configuration changes may take up to 59 minutes to apply across your environment.

ℹ️ Cached URLs containing the ignored parameter are removed from your cache automatically within 2 hours of adding the rule.

Return a 404 for specific URL patterns

Use this method when you want Prerender to stop serving specific URLs to AI crawlers and search engines entirely. When a URL matches a rule, Prerender returns an HTTP 404 response — signaling to crawlers that the page doesn't exist and should be removed from their index.

ℹ️ You can add up to 50 URL pattern rules. Contact support@prerender.io if you need more. Note that a large number of active rules may increase Prerender's response time, since every incoming URL is checked against the full list.

A contains rule checks whether the specified value appears anywhere in the full URL — including the domain, path, and query parameters.

Use the rule tester in your dashboard to confirm the rule matches only the intended URLs before saving.

Wildcard match

Wildcard rules use * to match flexible patterns within URLs. Here are examples of common wildcard patterns and their effects:

Pattern	Effect
`xyzxyz`	Excludes all URLs containing `xyzxyz`
`http://*`	Excludes all URLs starting with `http://`
`*.aspx`	Excludes all URLs ending with `.aspx`
`https://example.com/*`	Excludes all URLs beginning with `https://example.com/`

⚠️ Start your pattern with * if you want to match regardless of how the URL begins. For example, example.com/* will not match https://example.com/something because the pattern doesn't start with *.

Regular expression match

For cases where contains and wildcard matching aren't precise enough, Prerender can implement custom rules based on regular expressions. Contact support@prerender.io to set these up.

Adjust your integration

The most precise way to control what Prerender caches is to modify your integration so only the requests you want rendered are forwarded to Prerender in the first place. Filtering at the integration level is more efficient than using ignore rules — requests never reach Prerender, so they don't affect response time or your render limit.

See what integrations are available for Prerender for guidance on where to add filtering logic for your stack.

Configure your robots.txt

Configure your robots.txt file to direct compliant AI crawlers and search engines away from URLs you don't want indexed. Well-behaved crawlers — including Googlebot — follow robots.txt directives.

Prerender does not read your robots.txt file, but it serves whichever URLs crawlers request. Keeping your robots.txt well-configured means compliant crawlers are less likely to request those URLs. For guidance on syntax and best practices, see Google Search Central.

Render usage and ignore rules

URLs that match an ignore rule — whether a parameter rule or a URL pattern rule — are not counted against your render limit. If you're adding a large number of URL pattern rules, adjusting your integration to filter upstream is likely a better long-term approach for both performance and render efficiency.

💬 Still need help?
If you need help configuring URL ignore rules or setting up regular expression matching, our support team can help.
→ Contact us at support@prerender.io