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# Anonymous User ID for each sGTM Requests

Learn how to integrate hashed User ID as custom request header variables into your Server-Side Tag Manager (sGTM).

Source: https://usehardal.com/anonymous-user-id-for-each-sgtm-requests
Published: 2024-02-18
Updated: 2024-02-18
Author: Berkay Demirbas

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Unlike client-side tagging, server-side tagging allows you to manipulate data in each request to your website or app. 

While utilizing this manipulation structure in server-side requests for user privacy, you can also use it for hiding business sensitive data.

In this post, we will explore how each request to the server-side tag is anonymized by **Hardal** servers and how you can send the hashed `x-hardal-user-id` data as a variable from GTM to GA4.

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The `x-hardal-user-id` is created by combining a hash of the following elements:

- **User IP Address:** We do not store IPs, discard and redact on server logs them upon hash combination.
- **User-Agent:** This includes information about the user's device, such as Chrome, Firefox, etc.
- **Hostname:** This represents the user's request host name.

> You can only see this this data as request header on sGTM Preview mode. 

Learn how to configure your Server-Side Tag Manager to send the `x-hardal-user-id` data as a variable from Google Tag Manager (GTM) to Google Analytics 4 (GA4) or BigQuery. 

> Get details [here](https://usehardal.com/server-side-streaming-to-bigquery) about streaming to BigQuery from server-side GTM.

- Go to your server-side container
- Create a new user-defined variable called **User ID**
- Choose **Request Header**
- Name it `x-hardal-user-id`

![creating variable in server-side GTM](https://imge.usehardal.com/cdn/post-contents/Screenshot_2024-02-18_at_20.27.18_noixdf.png)

- Go to your server-side container
- Go to your **Google Tag** configuration 
- Add as user property your **User ID**

![Send Anonymous and Hashed User ID to GA4](https://imge.usehardal.com/cdn/post-contents/n98nmqg911kkqcbfrsj6.png)

> That's all, you can now override original user_id user properties with this hashed and secure value. 🔐

![server-side GTM custom request headers](https://imge.usehardal.com/cdn/post-contents/wszjszfszdkv5uf1ioew.png)

- **Enhanced User Privacy:** Implementing anonymization ensures that user data is protected, aligning with privacy regulations.
  
- **Accurate Analytics in BigQuery:** Sending the `x-hardal-user-id` data as a variable enhances the accuracy of analytics through Google Analytics 4 to BigQuery using server-side Google Tag Manager.

By following these steps, you can able to use server-side tagging for both user privacy and optimizing data handling within your server-side measurement stack.

Ready to take control of your server-side measurement? Sign up for a free trial or request a free demo to experience the new way of server-side tagging, without burnout! 🔥