A/B TESTING AT SCALE: HOW WE ENGINEERED A SOLUTION FOR MILLIONS OF USERS WITH AWS

Summary from the TLDR Web Dev newsletter

To conduct large-scale A/B tests without sacrificing user experience, Unacademy engineered a solution using AWS serverless tech. Instead of determining which test variant to show after the page loads (causing a distracting flicker), its team selected a test variant before the webpage even reached the user's browser. This was done by running code at the network edge to intercept requests, determine the variant, and fetch the appropriate content from the CDN.