How to create a Fullstack A/B experiment

Follow the steps below to set up a Fullstack test campaign and control your experiment logic directly from your code using Personizely’s JavaScript API.

⚠️ Note: This test type is designed for advanced users or developers. It does not use the visual builder and must be implemented in your codebase.

1. From your Personizely Dashboard, navigate to the Settings tab and click on Features:

This is where you define the features and parameters used in your test variations. Each feature can include one or more parameters of the following types:

• String (e.g. "Buy now", "red")

• Boolean (e.g. true)

• Number (e.g. 10)

Click + Add a feature, name it, and define its parameters.

2. From your Personizely Dashboard, navigate to the Campaigns tab and click the Create Campaign button at the top right:

3. In the “Create new campaign” window, select Full Stack Test, name your campaign, and define a hypothesis to clarify what you’re testing.

Click Create to continue.

4. You will be redirected to the campaign settings page. Under Variations, you'll see the Original (control group) and a default Variation 1.

You can rename the variation and click Create variation to add more.

5. To assign logic to a variation, click Edit next to it.

In the Variation features window, click + Add feature and select from features you’ve previously created under Settings → Features.

You can assign one or more features per variation.

6. Adjust Traffic allocation by setting the percentage of visitors that should be exposed to this campaign.

7. In the Goals section, select the action(s) you want to track, like Purchase or Add to cart.

You can assign multiple goals and mark one as the primary goal for reporting.

8. Fullstack tests are triggered in your code using Personizely’s JavaScript API:

Use the ply.runCampaign(id) method with your campaign ID to assign a visitor to a variation.

API Overview:

• ply.runCampaign(id) – runs the campaign, returns the variation or null (control group)

• variation.getFeature(key) – accesses a feature by its key

• feature.isEnabled() – returns true/false

• feature.getParameterValue(key) – retrieves the value of a feature parameter

Note: For the best no-flicker experience, make sure the Personizely script is loaded synchronously on your site.

🎉 Congratulations, your Fullstack test is now ready to go live!

**Learn more in the Fullstack Test documentation →

Updated on: 03/07/2025