How to check if Cloudflare Railgun is working


There are various ways you to confirm if Cloudflare Railgun is working on a website. Since Railgun inserts header information in to requests, you’ll need a way to check these headers. When looking at these headers, you’re looking for Cloudflare headers such as:

  • cf-railgun: e95b1c46e0 0.02 0.037872 0030 9878
  • cf-ray: 478149ad1570291

You can use the following methods to check the Railgun headers.

Using a browser

Most browsers offer built in options or plugins that can check headers.


Claire extension
If you use Google Chrome, Cloudflare has created a special browser extension called Claire that you can download and install:
If you have the Claire plugin enabled you’ll see a cloud icon (02 CloudFlare Railgun.fw.png) in your address bar.
In the cloud icon in the previous sentence, there are three letters: the second one is ‘R’. Since it’s NOT highlighted in this above image, it means Railgun is not enabled. Only when this character is highlighted does it confirm that Railgun is working.
Chrome Developer Tools
This is built into Chrome:
    1. On your keyboard, click CTRL + Shift + I. This opens Developer Tools.
    2. Click the 'Network' tab. Data collection starts when you hit F5 to refresh the page.
    3. Once you have network data listed, click on an object.
    4. Click on the headers tab to view the details.


  1. Click the ‘Develop’ tab.
  2. From the dropdown, choose ‘Show Web Inspector’.


  1. Install a tool such as Firebug:
  2. Once you open it, click on the ‘Net’ tab.
  3. Reload the page and you’ll then see the headers listed.

Using an online site

You can use an online site that tests your website and shows you headers such as

  1. Run a test of your website
  2. Click on an object that is being cached by Cloudflare on your site.
    03 CloudFlare Railgun.fw.png
  3. Click the 'Response' tab to the right of the request.

Using CURL

You can use CURL or other command line tools.

If you have access to a terminal, you can check using the CURL command or other command line tools that allow you to examine headers. To check, use CURL -I to show the headers only:

curl -I

See also

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Article last updated PST.