FPID Cookie for Google Analytics (What is it & What Does it Do?)

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For websites that utilize the universal analytics client within Google Analytics 4 for tracking and analytics on their site, The FPID cookie is a key part of the collection process. This cookie comes with the server-managed client option and creates new potential for sites to control more aspects of traffic and collection.

You have come to the right place if you want more information about the FPID cookie and its implications for sites looking to switch to a server-managed client. The cookie is a step up regarding security and control from the server owner’s side.

We’ll detail the FPID cookie’s function and how it works for those who want to understand it more deeply. If your site is looking to utilize the Server-managed option and implement FPID, we will also detail the process and its implications for your site.

Let’s dive in.

Inside the Universal Analytics Client within Google Analytics 4, you can switch to a Server-managed client for tracking and analytics on your site. With this switch, you can then utilize the FPID cookie to set and persist a unique ID for all visitors on the site.

With this unique ID, Google Analytics can uniquely track, attribute, and assign each visitor’s interactions. As a result, the data analytics collected from these visitors is more accurate and provides more valuable insight into your site’s events, requests, and performance.

Businesses that use their website to sell goods or promote services use Google Analytics to collect valuable information from consumers. The data they collect gives them a look into the type of visitors they have and how well different areas of their site perform.

Information like this is essential to optimizing website performance and identifying areas of weakness. However, to start this whole process and ensure its effectiveness, every visitor needs the unique ID set by the FPID cookie.

With an ID from the FPID cookie, how does Google Analytics collect visitor data? And how is this different than other identifying cookies used by Analytics? The way the FPID cookie securely collects data is what distinguishes it from other cookies used in JavaScript-managed clients.

The standard cookie that Google Analytics uses to assign a user ID is the cid (client ID) cookie. Google Analytics then sends an HTTP request to transfer the client ID from a browser to Google Analytics. Typically, the client ID is stored in a first-party cookie using JavaScript.

However, the difference with the FPID cookie lies in how a client ID is transferred and deciphered. The FPID cookie is set in HTTP and utilizes the HTTPOnly flag to set FPID as only accessible to server-side scripts.

This distinction provides an extra layer of security for client IDs and their associated data. The FPID cookie can not be accessed or read with JavaScript.

P.S. Understanding serverside tagging will make this article easier to follow. Find out more in this article.

To use the FPID cookie, select the server-managed option in your Universal Analytics Client. To further understand the implications of this and how it will affect data collection and client IDs on your site, let’s review both script options.


The default setting is for client IDs to be managed and read by JavaScript. As mentioned earlier, the ID is stored in the cid cookie on a user’s browser. Google Analytics processes and reads the ID with JavaScript for its purposes.


If you set the client ID option to server-managed, the FPID cookie will replace the cid cookie. The FPID cookie is then responsible for transferring the ID information to Google Analytics. However, the FPID side can only read the server cookie and is protected with the HTTPOnly flag.

Migration Option

A third option in the client ID settings is perfect for sites with several users with IDs but wish to switch to the server-managed option. This option is Migration, which allows you to switch to server-managed IDs stored by the FPID cookie without resetting your existing user IDs.

JavaScript Managed vs Server Managed

So, what are the primary differences between these two options? In simple terms, it determines if the cookie that contains a user’s Google Analytics ID is read by the browser-side script (JavaScript) or server-side (HTTP).

While there is nothing wrong with using JavaScript to access, read, and transfer information stored in cookies, HTTP has a few advantages. The primary one is an additional layer of security that prevents things like cross-site tracking, which many users find invasive.

Since the FPID cookies can’t be accessed or read by the browser script, they can’t be used to track a user’s behavior across sites. You can utilize FPID to create a safer, more private browsing environment for users.

Final Words

Google Analytics uses client IDs to assign unique IDs to users, persisting them to attribute behavior and collect data accurately. The standard Universal Google Analytics client setting allows client IDs to be managed by JavaScript (browser-side) cookies.

However, with the option to utilize server-managed client IDs, you can use the FPID cookie to store users’ IDs. The FPID cookie is an HTTP cookie that can only be read by the server, not the browser script.

This option establishes additional protection for users against cross-site tracking by using the HTTPOnly flag to ensure it is only accessed by server script with Google Analytics. No user’s information can be accessed from the browser, and users can enjoy your site in privacy while you still collect the valuable data you need.

Want to ensure your website is entirely compliant with all relevant regulations? Contact us for a free consultation today.

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