shiftzero

ShiftZero documentation

ShiftZero is edge experimentation infrastructure: A/B tests are applied in the HTML stream at the CDN, so the browser's first paint is already the variant — on any stack, with no client SDK and no application changes.

The loop

assign (edge) → transform (HTML + hydration + RSC) → expose → convert (browser)
      ↓                                                            ↓
  collect  →  analyze (peek-safe, CUPED, Bayesian)  →  ship the winner

A visitor hits your site through the ShiftZero edge. The edge deterministically assigns them to a variant, rewrites the streaming HTML (and the framework’s hydration data) to match, and records an exposure. In the browser, a tiny bridge mirrors the conversion events you already fire into the collector. The dashboard joins exposures to conversions with attribution rules and scores every metric with peek-safe statistics.

The pieces

ComponentWhat it does
DashboardThe control plane: author experiments (visual editor + code editors), targeting & audiences, live results, notifications, learnings.
Edge workerA reverse proxy in front of your origin: assignment, the streaming HTML/hydration/RSC transform, exposure beacons, identity, consent.
CollectorIngests exposure + conversion events (validated, rate-limited, key-authenticated) and serves reports.
Track bridge (sz.js)One script tag that mirrors your existing GA4/dataLayer events as conversions — your analytics are untouched.

Where to go next