LaunchDarkly

LaunchDarkly is a feature-flag management service that separates turning a capability on from deploying the code that contains it.

Code ships behind a condition whose value the service decides at runtime, so a capability can be enabled for a percentage of users or one segment and switched off again without a release if something breaks. The three main uses are gradual rollout, an emergency kill switch, and assigning users to the variants of an experiment. Two cautions: dead flags accumulate quickly into technical debt and untested code paths, and turning a flag on is not an experiment by itself. An effect claim holds only with random assignment, a control group and a metric chosen in advance.