How to Choose Testing Approach? Client-side or Server-side

Client-side testing is by far the most commonly-used solution employed by companies with A/B testing and personalization programs. But over time, many have come to realize this approach can clash with existing and emerging technologies, add performance challenges, create privacy concerns, and more. As a result, we’ve seen an increase in demand for a solution to tackle these increasingly-important issues.

This article will share a quick tip sheet on client-side vs server-side testing, providing a brief overview of both and the considerations to take into account before selecting either approach.

Table of contents

What is client-side testing?
What is server-side testing?
Which one is best?
Pros and cons of client-side testing
Pros and cons of server-side testing
So how do I choose?

What is client-side testing?

In this approach, testing and personalization is implemented utilizing in-browser javascript libraries. Built primarily for web personalization, it is marketer-friendly, giving users the ability to easily create experiences through the vendor’s user interface (UI).

What is server-side testing?

A server-side integration enables organizations to call the personalization service before the page is rendered and is built into the back-end of your web application tech stack. The more sophisticated method, personalization can be achieved beyond the web (kiosks, call centres, etc.) with a server-side approach.

Which one is best?

The longstanding client-side vs. server-side testing debate often concentrates on the question of convenience: which is easiest to integrate and test with?

Pros and cons of client-side testing:

• PRO: Business users can create experiences with ease
• PRO: Requires minimal development hours and time-to-deploy is quick
• CON: Can clash with existing technologies and emerging frameworks
• CON: Doesn’t allow brands to expand web experiences into other channels

Pros and cons of server-side testing:

• PRO: Wider range of capabilities with minimal to zero effect on site speed
• PRO: Allows brands to deliver tailored experiences across the customer journey
• CON: More difficult for set up and deploy
• CON: Designed for developers, therefore less business user-friendly

So how do I choose?

While there’s no simple answer, a few guidelines are:

1. If your primary users will be marketers and time-to-launch is their first priority, client-side is likely to be the best choice.
2. If your tech and R&D departments will be heavily involved, are planning on using more sophisticated integrations, or deploying experiences beyond the web, server-side is likely the answer you’re looking for.
3. A hybrid approach is also possible with some modern, personalization platforms, where pre-rendered server-side testing can coexist with traditional client-side testing.