# PlanetScale growth experiments

PlanetScale · July 2023
URL: https://www.edgarlr.com/work/planetscale-growth-experiments

A/B testing for PlanetScale’s marketing site, GrowthBook on top of the existing analytics, with variants assigned in edge middleware and served as prerendered static pages.

## Setup

Analytics was already in place; what was missing was a way to test against it. I
set up GrowthBook and wired it into our own analytics, a private package with its
own server, rather than a separate third-party pipeline.

The site was static and had to stay that way. The usual client-side variant swap
costs a flash of the original and a second render behind it. Assignment happens in
edge middleware instead: a cookie decides which variant a visitor is in, and the
request is rewritten to a separate prerendered route for it. Every variant is
built ahead of time, so the response is static either way.

Most of the work after that was verification: confirming each visitor saw the
variant they'd been assigned, every time, and that exposures and conversions were
measured correctly as they moved through Segment, our CDP. Tracking runs
server-side at the proxy, next to where assignment already happens. It held up
better than the client because it isn't dropped by ad blockers, so the counts are
closer to complete.

## Experiments

Three, once the setup held: one on the homepage, one across a few product pages,
and one on signup.

The homepage tested the control against a shorter, summarized version. The
summarized version performed better and became the default.

Signup tested the standard self-serve flow against sending people to contact
instead.