Sentry developed an experimentation system using Facebook's PlanOut library, which allows for easy and complex experiment writing, negligible performance impact, and measurable results. The system requires installing the SDK, sending an error, and defining a method `assign()` to determine user assignment to variants. Sentry ran an experiment where users were shown either a "See Sample Event" button or a more subtle link, with 12% improvement in activation rate for the button variant compared to the control group. The system logs exposure and events, integrates with the frontend using AJAX requests, and enables analysis of click-through rates and other metrics.