Start for free

Set up transformations

This guide details how to implement and manage transformations in Google Tag Manager (GTM) for Server-side Tracking with TAGGRS. At the bottom of the page, we included links to more in-depth resources about transformation types and practical applications so you can explore further as needed.
Favicon of TAGGRS Server-side Tracking
Typical use cases of trasformations in Google Tag Manager include filtering, modifying, or enriching data to improve data quality, enforce privacy compliance, and optimize event payloads for downstream analytics tools.

Create a new transformation

1.
Log in to Google Tag Manager.
2.
Select the relevant server-side container.
3.
In the left navigation, select Transformations.
4.
Click New to create a transformation.
what transformation look like in Google Tag Manager

Select transformation type

Choose from "Allow Parameters", "Exclude Parameters", or "Event Enrichment" based on your requirements.

GTM trasformazione types

For the demonstrative purpose of this guide, we chose "Event Enrichment E-commerce".

transformation types in Google Tag Manager

Configure parameters

1.
Specify which parameters to allow, exclude, or enrich.
2.
For enrichment, define the new parameter values or reference external data sources as needed (e.g., Firestore for e-commerce enrichment).
configuring the parameters of your transformation

Set priority

1.
Assign a priority to the transformation if multiple transformations could apply to the same data. Higher values are evaluated first.
setting priority to your transformation in Google Tag Manager
2.
If not set, the default evaluation order is: Allow Parameters → Event Enrichment → Exclude Parameters.

Set matching conditions

Define when the transformation should apply (e.g. always, or only when certain conditions are met).

setting matching conditions to your transformation in Google Tag Manager

Specify which tags the transformation should apply to. If left blank, the transformation applies to all tags in the container.

setting priority to your transformation in Google Tag Manager

Test in Debug Mode

1.
Open debug mode in both your web and server containers.
2.
Trigger relevant events on your site or via tools like Postman.
3.
Use the GTM debug interface to verify that transformations are applied as expected.
E-commerce parameters in FIrestore

Publish

Once verified, publish the updated server container to make the transformation live.

Best practices

  • Use transformations to enforce privacy by default: exclude or mask all PII unless explicitly needed.
  • Regularly audit transformation configurations to ensure compliance and data quality.
  • Test all changes in a controlled environment before deploying to production.

Transformation types

Transformation types in Google Tag Manager
Allow Parameters
Whitelist specific parameters to include in the event data object. Only these parameters will be processed and sent downstream.
Exclude Parameters
Blacklist specific parameters to remove from the event data object. Use this to strip out sensitive or irrelevant data.
Event Enrichment
Add or modify event data parameters. Useful for injecting additional context, correcting data, or appending values from external sources.

Practical applications

Data Anonymization
Mask IP addresses or other identifiers before analytics ingestion.
Data Enrichment
Add user segmentation, geolocation, or custom attributes to events.
Validation and Correction
Check and correct event data in real time.
E-commerce Data Augmentation
Enhance purchase events with additional product or transaction details.
Parameter Filtering
Remove redundant or non-compliant fields from event payloads.
Copyright © 2025 TAGGRS. All right reserved.
TABLE OF CONTENTS
Create a new transformationConfigure parametersSet prioritySet matching conditionsLink to TagsTest in Debug ModePublishBest practicesTransformation typesPractical applicationsUseful resources