Feature Flag Config Generator

A feature flag (also called a feature toggle or feature switch) is a configuration value that lets you enable or disable functionality in your application without deploying new code. Teams use flags to do gradual rollouts, A/B tests, kill switches, and trunk-based development where incomplete features are merged but hidden.

LaunchDarkly is a commercial SaaS platform with a rich targeting UI and analytics. Unleash is an open-source feature flag server you self-host. OpenFeature is a vendor-neutral CNCF standard that defines a common SDK interface — you can swap providers without changing application code. For small projects, a simple JSON file or environment variables may be all you need.

Use percentage rollout for gradual production launches — start at 5%, monitor error rates, then ramp to 100%. Use user segments when you want to target specific groups: beta testers, internal employees, paid users, or users in a specific region. Segments require user context in your evaluation call (user ID, group, attributes).

Boolean flags (on/off) are simplest and cover 80% of cases: enable a feature, run an experiment, kill-switch a service. Multivariate flags (string, number, JSON) are for A/B/n testing with more than two variants, configuration-as-flags (returning a JSON config object), or dynamically controlling rate limits and thresholds without a deploy.

These are distinct concepts. A disabled flag means the flag system returns the off/default variant regardless of targeting rules — it's an emergency stop. The default value is what gets served when no targeting rule matches. A flag can be enabled (targeting rules active) but still return false for most users if they don't match any rule.

Use kebab-case or snake_case, be descriptive, and include the domain: new-checkout-flow, enable-dark-mode, ai-summary-panel-v2. Avoid vague names like 'test' or 'experiment1'. Include the expected lifetime in the description — flags should be cleaned up once the rollout is complete.