Understanding the difference between client-side tagging and server-side tagging is critical to optimise user experience and data collection.
Google Tag Manager (GTM) supports both methods, but each serves different purposes and brings unique benefits.
Before we dive into the comparison, here’s a quick overview:
Client-Side Tagging
Client-side tagging involves executing all tags directly in the user’s browser or app.
It uses a single web container that holds all tags, triggers, variables, and related code. When a user interacts with a page, the container activates and loads the appropriate tags, which then send event data directly from the browser to various third-party tools and analytics platforms.
Server-Side Tagging
Server-side tagging, on the other hand, involves two containers: a web container that remains on the website or app and a server container that lives in a cloud environment.
The web container sends event data as HTTP requests to the server container. This server container then processes, modifies, and forwards that data to analytics and marketing platforms. It acts as an intermediary that you control.
Architecture Overview: Client-Side vs. Server-Side Tagging
In client-side tagging, all tracking operations, including data collection, transformation, and dispatching, are executed in the user’s browser or app.
This makes it easier to set up, but potentially less secure and more taxing on performance. Every interaction can result in multiple HTTP requests being sent out to different endpoints from the browser, leading to higher resource usage.
In contrast, server-side tagging separates these responsibilities.
The browser only sends one HTTP request per user event to the server container. The server container then takes care of generating and sending vendor-specific requests. This dramatically reduces the workload on the client, leading to better performance and giving you complete control over the data processing pipeline.
When to Use Each Tagging Method
Client-side tagging is ideal for simpler use cases where quick deployment is needed and performance or privacy concerns are minimal. However, for websites with high traffic volumes or stricter privacy needs, server-side tagging is more suitable and sustainable.
Here are the use cases and recommendations for tagging methods:
- Fast setup for simple tracking: Client-side tagging
- High privacy and control required: Server-side tagging
- High traffic websites: Server-side tagging
- Performance optimisation needed: Server-side tagging
- Cross-domain tracking: Server-side tagging (with the same container ID across domains)
Why Choose Server-Side Tagging?
Server-side tagging isn’t just a more secure way to collect data. It’s a smart, scalable, and future-ready upgrade for your digital ecosystem. Here’s why it might be time to transition:
1. Improve Website and App Performance
- Less code on the client side: Tags no longer run fully in the user’s browser.
- Fewer HTTP requests: One event request per interaction vs. many.
- Optimised load time: Especially helpful for marketing-heavy sites.
- CDN possibilities: Serve analytics libraries from your own domain for faster loading.
Result: Faster pages, lower bounce rates, and improved user experience.
2. Ensure Granular Data Privacy and Compliance
In the client-side model, user browsers send data directly to multiple vendors, making it harder to manage what gets shared. With server-side tagging:
- You own the data pipeline.
- Remove PII before it ever reaches a third-party endpoint.
- Operate in a first-party context, enhancing trust and compliance.
- Block third-party cookies if needed and enforce stronger security policies.
Result: You maintain control, ensure GDPR/CCPA compliance, and build user trust.
3. Improve Data Quality and Consistency
Data inconsistencies are common with client-side setups, due to browser variances, device behavior, and tag misfires. Server-side tagging solves this by:
- Validating event data before it’s sent out.
- Normalising information for consistent analytics reporting.
- Eliminating noise, such as redundant or faulty data.
Result: Better data for better decisions.
How to Get Started with Server-Side Tagging
If you’re ready to get started with server-side tagging, here’s how to begin:
- Create a tagging server using Google Cloud Platform’s App Engine.
- Deploy a server container in your GTM account.
- Configure your web container to forward events as HTTP requests to your server container.
- Set up processing rules within the server container to screen, validate, and enrich data.
- Forward the processed data to third-party platforms like Google Analytics, Ads, or other marketing tools.
- Monitor your server environment to ensure it performs well under load and complies with uptime standards.
💡 Pro Tip: Take advantage of Google’s “Server-Side Tagging Fundamentals” course to walk through each step in detail.
Important Considerations
- Cross-domain tracking must use the same container ID across all domains to preserve data continuity.
- Ensure your GCP setup is optimised to handle traffic levels.
- Monitor and maintain your tagging server for performance and uptime.
Server-side tagging is a strategic move toward data governance, performance optimisation, and future-proof compliance. While it requires a more involved setup, the long-term gains in control, accuracy, and security are well worth the investment.
Need a fresh perspective? Let’s talk.
At 360 OM, we specialise in helping businesses take their marketing efforts to the next level. Our team stays on top of industry trends, uses data-informed decisions to maximise your ROI, and provides full transparency through comprehensive reports.
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