Server-side testing
Running experiments in your own server or edge code rather than by changing the page in the visitor's browser.
In server-side testing, your server decides which variant a visitor gets and renders it directly, so there is nothing to swap in the browser. It suits changes the browser can't make: search ranking, pricing logic, recommendations, headless storefronts.
It needs a developer, and the same visitor must get the same variant on the server and in the browser.
A headless store tests two product recommendation models in its edge function and reports which one each visitor saw.
Related terms
- Feature flagA switch in your code, controlled from outside, that turns a feature on or off or serves a value to a chosen share of users.
- BucketingHow a testing tool assigns each visitor to a variant and keeps them there on later visits.
- FlickerWhen a visitor briefly sees the original page before a test's change replaces it.