Using Cloudflare Workers to Get Visitor Information

26 Feb, 2023

A little while ago I saw a blog post from that talks about how to get the public IP address using There are plenty of reasons to know your external IP address and plenty of sites out there to get this information.

To name a few others:

For the last year or two now, and started using Cloudflare for my websites DNS and Cloudflare Workers as well. Cloudflare Workers are a serverless execution environment to perform certain functions prior to a page loading, render its own content, or other serverless functions.

For some basic Workers you can use Cloudflare's Wrangler CLI or from within the dashboard. Some more advanced workers, using the CLI might be best. I setup a worker a while ago to track some visitor information like IP, location, etc. I don't store this information anywhere but could then leverage Cloudflare's edge network to route county origins to a EN, US,MX, CA version of my website. Sample worker for a county code redirect is here too.

You can setup your worker in the dashboard and it will give you a default * subdomain to start with. This is where the execution of the worker takes place, and if something is rendered to the browser, you'll see it here too. You will create your worker subdomain, then each worker has its own name as well. I created a worker called visitor.

Then for my worker, I added an event listener that will return a JSON object to the browser.

addEventListener("fetch", event => {
  const data = {
    ip: event.request.headers.get('cf-connecting-ip'),

  return event.respondWith(
    new Response(JSON.stringify(data, null, 2), {
      headers: {
        "content-type": "application/json;charset=UTF-8"

In this example we're using Cloudflare's event.request object from the browser session to Cloudflare's network. This has an object of the cf that holds data of what Cloudflare regional Colo the end user is connecting to. This is all data about the users connection to Cloudflare. This is how Cloudflare also uses this information to route visitors to the right edge network for the websites they host DNS for.

In our worker this is all in the data object and then we tell the worker to return the data in a JSON format and set the pages header content-type to application/json;charset=UTF-8.

Since this is all part of what Cloudflare knows of a user, it doesn't keep the users IP in the cf, but we can still access the sessions header request and pull out the cf-connecting-ip. This will hold your visitors IP address. There are plenty of other HTTP Request headers to look at as well.

Cloudflare allows you to add a Custom Domain our Route for your worker. For my use case on this one I added a Route for

The part that was a little confusing was the DNS record for my website and Zone. By creating an A record for, pointing it to, and proxying it through Cloudflare, this tells the DNS to go to my worker subdomain and run the worker code.

You could set your own worker up and use it in your scripts as well. Maybe even use Select-Object with PowerShell to get just the IP address, or any of the values. How else are you going to use Cloudflare Workers, the Examples have an expansive array of how to implement them.

I'm publishing this as part of 100 Days To Offload. You can join in yourself by visiting

Tags: web design, 100DaysToOffload


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1 Reply

Adam Adam
@cjerrington Thanks for the shout out. Nice post to take things in another direction.

Found an issue? Edit on Github

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