Feature Flag System

This implements a complete feature flag system for controlling rollouts, A/B tests, and kill switches. You get flag evaluation with rules based on user attributes, percentages, and time windows, plus variant support for experiments. The references include a TypeScript service, React hooks, analytics integration, and even an admin UI. Honestly, this is the kind of thing you'd normally reach for LaunchDarkly or Split for, but if you need flags without the SaaS dependency or want full control over the data, this gives you a solid foundation. Just don't forget the cleanup part, abandoned flags pile up fast.

skills.sh installs: 445
GitHub stars: 379
last updated: Aug 21, 2026

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Install

$ npx -y skills add aj-geddes/useful-ai-prompts --skill feature-flag-system --agent claude-code

Installs into .claude/skills of the current project.

Files

Overview

Implement feature flags to decouple deployment from release, enable gradual rollouts, A/B testing, and provide emergency kill switches.

When to Use

Gradual feature rollouts
A/B testing and experiments
Canary deployments
Beta features for specific users
Emergency kill switches
Trunk-based development
Dark launching
Operational flags (maintenance mode)
User-specific features

Quick Start

Minimal working example:

interface FlagConfig {
  key: string;
  enabled: boolean;
  description: string;
  rules?: FlagRule[];
  variants?: FlagVariant[];
  createdAt: Date;
  updatedAt: Date;
}

interface FlagRule {
  type: "user" | "percentage" | "attribute" | "datetime";
  operator: "in" | "equals" | "contains" | "gt" | "lt" | "between";
  attribute?: string;
  values: any[];
}

interface FlagVariant {
  key: string;
  weight: number;
  value: any;
}

SKILL.md on GitHub