Last Updated: Jul 19, 2022
documentation for the dotCMS Content Management System

dotCMS includes an app that can be used to connect to and control, a web service that can be used to improve SEO rankings for client-side rendered Javascript/SPA pages. The dotCMS Prerender app does this by intercepting requests by indexing bots, such as Googlebot or Bingbot, and then proxying the request to the service. This service does the work of “prerendering” the Javascript app, including any content that is returned by client-side API calls. It then returns the resultant rendered — or “hydrated” — HTML to dotCMS and finally to the request for indexing.

To use this app, you will need either an account with or to have set up your own instance of the open-source application, which can be connected to and used by your dotCMS instance.

How the App Works

  1. It first performs a check to see if we should show a prerendered page.
    1. Check if the request is from a crawler — as defined in the crawlerUserAgents or if the request has an _escaped_fragment_ in its URL.
    2. Check to make sure we aren't requesting a resource — such as JS, CSS, etc.
    3. (optional) Check to make sure the URL is in the whitelist.
    4. (optional) Check to make sure the URL isn't in the blacklist.
  2. Make a GET request to the Prerender service (PhantomJS server) for the page's prerendered HTML.
  3. Return that HTML to the crawler.


Prerender Service URL

Defaults to the service at If you've deployed the opensource service on your own infrastructure, you can set the URL so that it points there instead.


This is the token from your account used to validate the prerender request.


If you specifically want to make sure that the Prerender service queries using HTTPS or HTTP protocol, you can set the init-param protocol to https or http respectively. Should generally be https.


This is a comma-separated list of URL regular expressions (regexes) that will be sent to for rendering.



This is a comma-separated list of URL regexes that will never be sent to for rendering.

Example: /images/.*,/css/.*


This is a comma-separated list of strings that will be matched against the request's User-Agent header. If one of these strings match, the request will be proxied to

Example: googlebot,bingbot


Important for servers behind a reverse proxy that need a different public URL to be used for prerendering.


You can test if your requests are being prerendered by setting the correct User-Agent header in a page request. For example:

curl --head -H 'User-Agent: googlebot' 

This will give you back a Prerender request header — something like:

x-prerender-requestid: 28fcca74-71a4-4b5f-a293-380e81ec4cac

Note on Hashbang Navigation

If you are using a # in your URLs, make sure to change it to #!, known as the hashbang character.

For hashbang URLs

To see:http://localhost:3000/#!/profiles/1234
Go to:http://localhost:3000/?_escaped_fragment_=/profiles/1234

For push-state URLs

To see:http://localhost:3000/profiles/1234
Go to:http://localhost:3000/profiles/1234?_escaped_fragment_=

For general information about AJAX crawling, read more about Google's protocol here.

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