A/B Testing Backend

ELI5 — The Vibe Check

A/B testing backend is the server-side logic that splits users into groups and tracks which version performs better. User group A gets the old checkout, group B gets the new one. The backend tracks conversions and declares a winner. It's science experiments for software.

Real Talk

Backend A/B testing infrastructure manages experiment assignment, traffic splitting, and metric tracking on the server side. It includes hashing user IDs for consistent bucket assignment, storing experiment configurations, logging exposure events, and providing APIs for experiment results analysis. Server-side testing avoids layout flicker and works for API-only changes.

Show Me The Code

function getExperimentVariant(userId, experimentName) {
  const hash = murmurhash(userId + experimentName);
  const bucket = hash % 100;
  const experiment = experiments.get(experimentName);
  
  if (bucket < experiment.trafficPercent) {
    return bucket % 2 === 0 ? 'control' : 'variant';
  }
  return 'control';
}

When You'll Hear This

"The A/B test shows the new checkout flow has 15% higher conversion." / "Assign users to experiment buckets on the backend for consistent experiences across devices."