Imagine deploying new code to production… without making the feature visible to users yet. Sounds like magic?

That’s exactly what Feature Flags (also called feature toggles) allow you to do.

🧠 What is a feature flag?

A feature flag is a technique that lets you turn features on or off in your application without deploying new code.

You wrap parts of your code in conditional logic, like this:

if (isFeatureEnabled('new-dashboard')) {
  showNewDashboard();
} else {
  showOldDashboard();
}

You can control this flag through a config file, an environment variable, a dashboard, or even a remote service.

🚀 Why use feature flags?

Feature flags give you control over when and how a feature is released.

They let you:

  • ✅ Deploy code without releasing it to users yet
  • ✅ Gradually roll out a feature to a subset of users
  • ✅ Test features in production safely
  • ✅ Turn off a feature instantly if it causes issues
  • ✅ Run A/B tests or experiments

In short: they separate deployment from release.

🎯 Real-world use cases

1. Soft launches / gradual rollouts

Release a new feature to 10% of users, then 50%, then 100%.

2. Internal testing

Enable a new feature only for internal teams or admins.

if (user.role === 'admin' && isFeatureEnabled('beta-tool')) {
  renderBetaTool();
}

3. Kill switch

If a feature causes issues in production, just turn it off—no rollback or hotfix needed.

4. A/b testing

Show different versions of a page to test which one performs better.

🛠️ How feature flags are managed

You can manage flags in various ways depending on the complexity of your app:

  • 🧪 Simple flags with environment variables or config files
  • ☁️ Remote config with third-party tools
  • ⚙️ In-house flag systems for full control

🧰 Tools you can use

  • LaunchDarkly – Feature management platform with fine-grained control
  • Unleash – Open-source feature toggle system
  • Flagsmith – Feature flag service with remote config
  • Split.io, ConfigCat, Firebase Remote Config, etc.
  • Or even custom logic using JSON files, DB tables, or flags per user/session

⚠️ Best practices

  • Give each flag a clear name and purpose
  • Clean up old flags once a feature is fully launched
  • Avoid too many nested flags—they make the code harder to read
  • Track flag usage in logs or analytics if possible
  • Group flags logically (e.g., by team, feature, or experiment)

🧠 Conclusion

Feature flags let you ship code safely, flexibly, and continuously. They’re a core part of modern deployment strategies—especially when paired with CI/CD, canary releases, and experimentation.

By using flags, you gain the power to decouple code changes from feature launches, test in production, and avoid risky all-or-nothing deployments.

In short: feature flags give you confidence to move fast, without breaking everything.