Feature Flagging
A software development practice that allows teams to enable or disable features for specific user segments without deploying new code — the technical foundation of modern experimentation.
Feature flags (also called feature toggles) are the bridge between engineering and experimentation. They allow teams to deploy code to production without exposing it to all users, then gradually roll it out — first to internal testers, then to a percentage of users, then to everyone.
Feature Flags and A/B Testing
Every modern A/B test is essentially a feature flag with measurement attached. The variant is "flagged on" for a random subset of users, and the experimentation platform measures the difference in behavior. This is why feature flag platforms (LaunchDarkly, Statsig, Split) and experimentation platforms are converging.
The Operational Value
Beyond experimentation, feature flags enable: instant rollbacks (if a release causes problems, toggle it off), canary deployments (release to 1% of users first), and gradual rollouts (increase from 10% to 25% to 50% based on monitoring). This dramatically reduces deployment risk.
For CRO Analysts
Understanding feature flags separates senior CRO analysts from junior ones. If you can speak the language of feature flags, you can partner with engineering to run experiments faster. You don't need to write code — you need to understand how experiments are deployed, how users are assigned, and how flags interact with each other.
Practical Application
If your organization doesn't use feature flags, it's the single highest-leverage investment you can make in experimentation infrastructure. Start with a managed service (LaunchDarkly, Statsig) rather than building your own. The ROI comes from velocity — you'll run 2-3x more experiments per quarter.