Android feature flags: Kotlin practices

Mon Jun 23 2025

You know that sinking feeling when you push a new feature to production and suddenly realize it's breaking for 10% of your users? Yeah, we've all been there. Feature flags are basically your safety net - they let you turn features on and off remotely without pushing a new APK to the Play Store.

If you're building Android apps with Kotlin, feature flags can save you from those 2 AM panic attacks. They're not just about risk mitigation though; they're also your ticket to running proper A/B tests and rolling out features gradually to see how users actually respond.

Introduction to feature flags in Android with Kotlin

Let's start with the basics. Feature flags are just boolean switches that control whether a piece of code runs or not. The magic happens when you can flip these switches remotely - no app update required.

Here's why they're particularly useful for Android development:

  • You can disable broken features instantly (no waiting for Play Store review)

  • Test new features with just your beta users first

  • Run A/B tests to see which version performs better

  • Roll out gradually to catch issues before they affect everyone

The real power comes from being able to change your app's behavior on the fly. Say you launch a new checkout flow and conversion drops - you can roll back immediately while you figure out what went wrong. Or maybe you want to test whether users prefer a bottom navigation bar or a hamburger menu. Feature flags let you run that experiment without maintaining two separate codebases.

Setting up feature flags in your Android app is pretty straightforward. You'll need to create a simple UI, add the necessary dependencies, and initialize the SDK. Once that's done, you can start fetching and using flags throughout your app.

The key is to follow some solid practices from the start. Bad feature flag hygiene leads to spaghetti code faster than you can say "technical debt". But get it right, and you'll wonder how you ever shipped features without them.

Implementing feature flags in Kotlin applications

Time to get our hands dirty. First thing you'll need to do is add the feature flag SDK to your project. Drop this into your app's build.gradle file - the exact dependencies will vary based on which service you're using.

Once you've got that sorted, initialize the SDK in your Application class. This ensures your flags are ready to go as soon as your app starts up. Most SDKs will automatically fetch the latest flag configurations, but you'll want to handle offline scenarios gracefully.

Here's where things get interesting. Don't scatter flag checks all over your codebase - that's a recipe for chaos. Instead, create a centralized feature flag manager. This gives you one place to:

  • Check flag status

  • Handle fallback values

  • Log flag usage for debugging

  • Mock flags for testing

The team at Quash wrote a great piece on encapsulating flag logic that really drives this point home. Your view models and activities shouldn't know or care where flag values come from - they just need to know if a feature is enabled or not.

Most feature flag services provide real-time synchronization, which means you can update flags and see changes instantly in your app. Just be smart about when you trigger syncs - you probably don't need to check for updates every time a user scrolls. Key lifecycle events like app launch or user login are usually good trigger points.

Best practices for managing feature flags in Android apps

Let's talk about what separates good feature flag usage from the kind that makes your future self hate your current self. Naming is everything. I've seen codebases with flags named "test_flag_3" and "new_thing_enabled" - don't be that person.

Use clear, descriptive names that tell you exactly what the flag controls. The folks at Flagsmith suggest using prefixes like "FF_" or suffixes like "_FEATURE" to make flags easily searchable. Something like FF_CHECKOUT_V2_ENABLED is infinitely better than new_checkout.

Here's a pattern that's saved me countless headaches: create a feature flag provider interface. This abstraction lets you:

  • Switch between local and remote flags easily

  • Mock flags in tests

  • Add logging or analytics

  • Implement fallback behavior

The biggest mistake I see? Leaving old flags in the code forever. Dead flags are like commented-out code - they confuse everyone and serve no purpose. Set up a regular review process. Statsig's management console actually helps track which flags are still being checked, making cleanup way easier.

If you're building an Android library, feature flags need extra thought. You can't just hardcode flag checks - library users need control too. The Android dev community on Reddit had a solid discussion about exposing clean APIs for flag configuration. Document which flags exist and what they do - your users will thank you.

Advanced techniques: A/B testing and gradual rollouts with feature flags

This is where feature flags really shine. Instead of just on/off switches, you can use them for sophisticated release strategies. Gradual rollouts let you test the waters before diving in headfirst.

Picture this: you've rebuilt your home screen, and it looks amazing in testing. But will real users love it? Start by enabling it for 5% of users. Monitor your metrics. If engagement drops, you've only affected a small group. If it improves, bump it to 25%, then 50%, then everyone. Medium's engineering team has a great writeup on how they approach controlled rollouts.

A/B testing takes this further. Instead of just rolling out gradually, you're comparing options:

  • Does a blue or green CTA button get more clicks?

  • Do users prefer infinite scroll or pagination?

  • Which onboarding flow has better retention?

Martin Fowler's classic post on feature flags explains how this isn't just about UI tweaks - you can test entirely different algorithms or architectures.

The secret sauce is measurement. You need to track how each variant performs. Tools like Statsig give you built-in analytics dashboards showing exactly how your features impact key metrics. Without data, you're just guessing.

Remember those best practices we talked about? They become critical when you're running multiple experiments. Clean code, clear naming, and regular cleanup prevent your app from becoming an unmaintainable mess of nested if statements.

Closing thoughts

Feature flags have transformed how I ship Android apps. Gone are the days of crossing my fingers during every release, hoping nothing breaks. Now I can roll out confidently, test with real users, and roll back instantly if needed.

The key is starting simple - maybe just one flag for your next risky feature. Get comfortable with the workflow, establish good patterns, and gradually expand from there. Before you know it, you'll have a robust system for experimentation and safe releases.

Want to dive deeper? Check out:

Hope you find this useful! Now go forth and flag those features - your future self will thank you when that experimental feature needs to be turned off at 2 AM on a Sunday.



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