{"id":93517,"date":"2024-12-26T11:41:36","date_gmt":"2024-12-26T06:11:36","guid":{"rendered":"https:\/\/vwo.com\/blog\/?p=93517"},"modified":"2025-04-30T18:17:40","modified_gmt":"2025-04-30T12:47:40","slug":"feature-flags-mobile-app","status":"publish","type":"post","link":"https:\/\/vwo.com\/blog\/feature-flags-mobile-app\/","title":{"rendered":"How to use feature flags for mobile app releases"},"content":{"rendered":"\n

As Christmas and New Year draw closer, your marketing team is gearing up to boost your app downloads<\/a> during the festive rush.<\/p>\n\n\n\n

You want to make the most of it and launch a new feature, \u201cHome screen banner,\u201d to showcase offers and maximize conversions in your app. <\/p>\n\n\n\n

Everything looks perfect during testing, but users report crashes after the update.<\/p>\n\n\n\n

Fixing this issue isn\u2019t straightforward. You must prepare a bug fix, submit it to app stores, and await approval.<\/p>\n\n\n\n

Even after the update is live, it depends on users manually downloading it. Meanwhile, your app\u2019s reputation takes a hit, and frustrated users uninstall it. <\/p>\n\n\n\n

This makes timely bug fixes nearly impossible and creates a stressful mobile app release cycle.<\/p>\n\n\n\n

Such challenges, unique to mobile apps, make quick updates and smooth rollouts a constant struggle for developers.<\/p>\n\n\n\n

Enter feature flags.<\/p>\n\n\n\n

\"How<\/figure>\n\n\n

What are feature flags?<\/h2>\n\n\n

Feature flags<\/a> (also known as feature toggles<\/a>) are essentially conditional statements within the code that allow developers to turn features on or off during runtime. They are implemented using conditional feature branches in the code, making logic available only to certain groups of users at a time.<\/p>\n\n\n\n

\"Feature
Feature Flags in VWO<\/figcaption><\/figure>\n\n\n\n

Let\u2019s dig deeper and understand the challenges in mobile app release management and how feature flags could be useful.<\/p>\n\n\n

Challenges of mobile app release management<\/strong><\/h2>\n\n

Delayed approvals and updates<\/h3>\n\n\n

Releasing updates for mobile apps comes with a unique roadblock: app store approvals. Once you submit this update, app stores like Android’s Google Play or iOS’s App Store review it.<\/p>\n\n\n\n

The review process can take anywhere from a few hours to several days. <\/p>\n\n\n

\n
\"Gif\"<\/figure>\n<\/div>\n\n\n

All iOS apps undergo manual reviews, typically taking 24-48 hours to complete. Manual reviews on Android are less frequent but can take over seven days when required.<\/p>\n\n\n\n

If the app doesn\u2019t meet their strict guidelines, it might be rejected, causing further delays. Meanwhile, your competitors might roll out similar features faster, leaving you disadvantaged.<\/p>\n\n\n\n

Even after approval, users must manually download the update. Many users delay or skip updates altogether, which means they miss out on the latest features. <\/p>\n\n\n\n

This lack of control over adoption adds unpredictability to the release cycle.<\/p>\n\n\n

Risk of bugs and user churn<\/h3>\n\n\n

You released a new \u201cOne-Tap Checkout\u201d feature, but a bug causes payment failures. <\/p>\n\n\n\n

Fixing this bug isn\u2019t instantaneous. Your team must prepare a fix and submit it for approval. We hope users download the update quickly.<\/p>\n\n\n\n

Users may face frustrating experiences during this lag, such as failed transactions. <\/p>\n\n\n\n

These frustrations can lead to bad reviews, uninstalls, or users switching to competitors. This domino effect can hurt not just your app\u2019s reputation but also your revenue.<\/p>\n\n\n

\n
\"Gif\"<\/figure>\n<\/div>\n\n\n

Every minute matters in mobile apps. Delayed fixes damage user trust and increase the likelihood of churn.<\/p>\n\n\n

Complexities in production testing<\/h3>\n\n\n

Continuous delivery means apps stay competitive by regularly delivering updates. However, mobile apps require code submission, app store approval, and user action to update.<\/p>\n\n\n\n

Moreover, testing apps in production is risky, so teams resort to traditional quality assurance methods, such as lab testing and \u201cdogfooding,\u201d where employees use the product internally before public release.<\/p>\n\n\n\n

Internal testers often bring biases due to their familiarity with the features, and controlled environments rely on simulated data, devices, and network speeds, making it impossible to cover all real-world scenarios or user types.<\/p>\n\n\n\n

Additionally, testing all these combinations takes time and resources. Any missed edge case could result in crashes or glitches, further complicating the release process.<\/p>\n\n\n

How feature flags help<\/strong><\/h2>\n\n

Decoupling deployment from release<\/h3>\n\n\n

Feature flags enable teams to continuously deploy code to production, even with incomplete features, without immediately exposing those features to users. <\/p>\n\n\n\n

This practice called trunk-based development, allows developers to merge their code frequently into the main branch.<\/p>\n\n\n\n

Feature flags act as conditional switches, controlling the visibility and execution of the new code. This means the code is deployed but remains inactive for users until the feature flag is toggled on.<\/p>\n\n\n\n

\"Decouple<\/figure>\n\n\n\n

For example, consider introducing a \u201cOne-Tap Checkout\u201d feature in an e-commerce app. After code deployment, the feature remains hidden from real users while an internal team of users or a small test group validates its performance and integration with payment systems. <\/p>\n\n\n\n

This approach allows live testing in real-world conditions without disrupting the user experience<\/a>. Teams can gradually enable the feature for select users, gather feedback, and address any issues before a full release. <\/p>\n\n\n\n

By separating deployment from release, feature flags reduce risk, improve development workflows, and ensure smoother, more controlled launches.<\/p>\n\n\n

Real-time control with a kill switch<\/h3>\n\n\n

A kill switch is a lifesaver for managing unexpected issues in production. If a feature causes performance issues or crashes for real external users, the feature flag allows you to disable it instantly without submitting a patch through the app store.<\/p>\n\n\n\n

Imagine rolling out a new form-autofill feature, and users report app crashes. With a feature flag, you can toggle off the feature for everyone while investigating the root cause. Users don\u2019t need to update their apps, ensuring a seamless experience.<\/p>\n\n\n\n

\"Real<\/figure>\n\n\n\n

This real-time control saves time and protects your brand\u2019s reputation by reducing downtime and avoiding bad reviews. Teams can address problems calmly instead of rushing through emergency patches.<\/p>\n\n\n

Gradual rollouts and testing in production<\/h3>\n\n\n

Instead of releasing a feature to your entire user base, you can progressively roll it out to smaller segments and monitor its performance.<\/p>\n\n\n\n

For instance, if you\u2019re launching a \u201cVoice Search\u201d feature, you can enable it for 10% of your users first. This helps you collect valuable feedback and identify potential issues before scaling it to 100% of your audience. <\/p>\n\n\n\n

\"Voice<\/figure>\n\n\n\n

You can even target specific user groups, such as premium subscribers or users in a particular region, for more controlled testing.<\/p>\n\n\n\n

Let’s explore some real-world use cases that feature flags can offer you.<\/p>\n\n\n

Feature flag use cases<\/strong><\/h2>\n\n

A\/B testing for data-driven decisions<\/h3>\n\n\n

You\u2019re developing a mobile shopping app and want to determine if users prefer a grid or list view for product displays. <\/p>\n\n\n\n

Instead of guessing, you can use A\/B testing<\/a> with feature flags to show the grid view to half of your users and the list view to the other half. By analyzing which group makes more purchases or spends more time browsing, you can decide which layout works better. <\/p>\n\n\n\n

Feature flags make it easy to run this experiment without needing separate app versions or updates.<\/p>\n\n\n

Personalized user experiences<\/strong><\/h3>\n\n\n

Suppose you have a news app that covers a wide range of topics. You can use feature flags to personalize content for each user based on their reading habits. <\/p>\n\n\n\n

If someone often reads sports articles, you can enable a \u201cSports Highlights\u201d feature just for them. This way, every user gets a customized experience that keeps them more engaged, all controlled through feature flags without additional app updates.<\/p>\n\n\n

Marketing campaigns to drive signups<\/h3>\n\n\n

Think about a music streaming app launching a new \u201cHi-Fi Audio\u201d feature. To attract new users, you can use feature flags to offer this feature exclusively to people who sign up during a promotional period or use a promotional code.<\/p>\n\n\n\n

You might also give early access to influencers or loyal users to create buzz. Feature flags allow you to control who gets access and when helping to drive signups and build anticipation.<\/p>\n\n\n

Subscription management across different levels<\/h3>\n\n\n

In a language learning app with free and premium tiers, you might offer basic lessons to everyone but reserve advanced grammar exercises for premium subscribers. <\/p>\n\n\n\n

Feature flags let you manage these access levels easily. If a user upgrades to premium, you can instantly unlock the advanced features without requiring an app update or reinstall, enhancing their experience immediately.<\/p>\n\n\n

Opt-in early access campaigns<\/h3>\n\n\n

Consider a photo editing app developing a new set of filters. You can invite users to opt in for early access to test these filters before they\u2019re officially released. <\/p>\n\n\n\n

Users who join get to play with new features and provide valuable feedback. Feature flags make it simple to manage who has access, and users feel rewarded for their participation with sneak peeks and perhaps exclusive perks.<\/p>\n\n\n

Regional feature control for compliance<\/h3>\n\n\n

Take a messaging app with a feature that allows disappearing messages. However, this feature isn\u2019t allowed in certain countries due to legal restrictions. <\/p>\n\n\n\n

With feature flags, you can disable the disappearing messages feature for users in those regions while keeping it active elsewhere. This ensures you comply with local laws without affecting users in other areas.<\/p>\n\n\n

Seasonal promotions and features<\/h3>\n\n\n

Suppose you run a mobile game and want to celebrate Halloween with special in-game events and decorations. Feature flags let you activate these seasonal features at just the right time and turn them off afterward. <\/p>\n\n\n\n

Players can enjoy limited-time challenges and rewards, making the game feel fresh and exciting. You can manage all this remotely without forcing players to download an update.<\/p>\n\n\n

Dark launches to test backend performance<\/h3>\n\n\n

Let\u2019s say you\u2019re upgrading your video streaming app\u2019s backend to support higher-resolution videos. Before rolling it out to everyone, you can use feature flags to enable the new backend for a small percentage of users without them knowing. <\/p>\n\n\n\n

This \u201cdark launch\u201d helps you monitor performance and fix any issues in a real-world setting. If problems occur, you can quickly switch users back to the old backend using the feature flag.<\/p>\n\n\n\n

There are so many examples where feature flags could be handy. While you may be convinced to start with feature flags immediately in your projects, let\u2019s look at some best practices around using feature flags first.<\/p>\n\n\n

Best practices for using feature flags<\/strong><\/h2>\n\n

Use clear naming conventions<\/h3>\n\n\n

When teams manage multiple feature flags, clear naming conventions are critical. A poorly named flag, such as flag1, can confuse team members and lead to errors during deployment.<\/p>\n\n\n\n

Instead, use descriptive names like CheckoutButton_Test_A or BetaAccess_LoyaltyProgram<\/em><\/strong>. This helps everyone on the team understand the purpose of each flag at a glance. <\/p>\n\n\n\n

Consistent naming across projects also prevents accidental activation or deactivation of the wrong flag, ensuring smoother operations.<\/p>\n\n\n

Assign ownership to each flag<\/h3>\n\n\n

Every feature flag should have an assigned owner, such as a product manager or developer. This person is responsible for the feature flag\u2019s lifecycle, including its creation, monitoring, and removal.<\/p>\n\n\n\n

For example, if a \u201cHoliday Discounts\u201d flag is no longer needed after the campaign, the owner ensures it\u2019s retired promptly. Ownership reduces the risk of forgotten flags cluttering the codebase and keeps the system manageable.<\/p>\n\n\n

Plan for dependencies<\/h3>\n\n\n

Feature flags often depend on other flags or features. For instance, a \u201cPromotional Banner\u201d flag may rely on a \u201cNew Campaign Backend\u201d flag. Without proper planning, activating one flag while another is off can lead to broken functionality or crashes.<\/p>\n\n\n\n

Mapping dependencies between flags before rollout helps avoid such conflicts. Use diagrams or documentation to outline relationships and test various combinations to ensure compatibility. <\/p>\n\n\n\n

By following these best practices, teams can effectively leverage feature flags, ensuring agility while maintaining clean and manageable code.<\/p>\n\n\n\n

Using a specialized third-party platform for feature management can save you the hassle of building a complex system in-house, letting you concentrate on developing your app\u2019s core features. Let\u2019s see how to choose a good platform.<\/p>\n\n\n

Managing the lifecycle of feature flag service<\/h2>\n\n\n

To effectively implement feature flags and prevent them from accumulating and becoming technical debt, you can implement the following process:<\/p>\n\n\n\n

1. Initial:<\/strong><\/p>\n\n\n\n