What are feature flags? Best practice guide

Feature flags are a valuable tool in software development. They function like switches, enabling developers to turn specific features on or off as needed.

It’s similar to having a remote control for your software—you decide which parts to show to users and when.

Developers use feature flags to introduce new product features or changes to a small, select group of users before rolling them out to everyone else.

Think of it like a soft launch, where you can gather feedback and fix any issues before a bigger reveal. It’s about making sure things run smoothly for everyone involved.

Feature flag example

Suppose a company wants to add a new task management feature to its project tool.

After developing the functionality, the company uses a “TaskManagementFeature” flag to control the release.

They initially set the flag to “off,” meaning they hide the new feature from users. This gives developers and QA teams time to test it to ensure it works correctly.

The company then rolls out the task management feature to a small group of users (beta testers). This means turning the feature flag “on” for these folks so they can access it and provide feedback.

Feedback enables the company to adjust and improve the feature. Developers can continue working on the feature in the background, making changes while the flag remains “on” for the beta group.

If the beta phase goes well and the company feels confident about the feature, they might deploy it to more users—this is a “limited release.” A limited release enables them to monitor the feature's performance among a larger audience. They can quickly turn the feature flag “off” if anything goes wrong.

The big launch only happens after any problems have been ironed out and everything is running smoothly. The feature then stays on permanently; now, everyone can use the new task management feature.

This way of releasing new features means the company can introduce and test it with minimal risks and maintain a positive user experience.

Feature flag benefits

From enabling seamless phased rollouts and A/B testing to reducing deployment risks, feature flags offer a versatile way for developers to innovate and iterate confidently.

Let’s look at some of the benefits of feature flagging.

• Risk mitigation: Feature flags reduce risk by providing a safety net. If a newly released feature causes issues, developers can instantly turn it off and minimize the user impact. They can then tackle the problem without affecting the entire user base.
  
• Continuous deployment: They enable continuous deployment by separating feature releases from code deployments. This enables developers to make changes without disrupting the app, leading to faster and more agile development.
• A/B testing and experimentation: A/B testing is a big part of many company experimentation strategies, and feature flagging helps make it happen. They can test different versions of a feature on different user groups to get valuable insights into user behavior and preferences.
• Phased rollouts: Feature flags enable phased rollouts, enabling new elements to be gradually introduced to a limited audience before a full-scale release. This controlled approach helps developers monitor system performance, collect user feedback, and spot problems early, ensuring a smooth and successful launch.
• Rollback capabilities: If a feature experiences unexpected problems, developers can quickly revert to the previous state by turning off the feature flag. Rollback capabilities ensure system stability and reduce downtime during post-release issues.

You can use feature flags in many scenarios to improve the software development process and deliver user-centric solutions.

Here’s how you can apply them in different contexts.

Canary launches

Canary launches involve rolling out a new software version to a small subset of users before releasing it to the entire user base—feature flags are great for implementing this. o

They let developers control which users or groups receive the new version to detect problems and offer a smoother experience for all customers once the full launch happens.

Testing in production

Feature flags enable testing without risking the user experience. Developers can introduce changes to users, monitor the system's behavior, and collect feedback. If problems happen, they can switch off the feature flag and return to the stable version.

This approach provides more realistic testing scenarios and helps identify potential issues that might not appear in artificial environments.

Production experiments

Businesses can use feature flags to release multiple versions to different user segments and collect data on how users behave and what they like.

A data-driven process enables them to make informed decisions based on genuine user interactions, leading to more meaningful product enhancements.

Implementing feature flags involves several steps to ensure you use them effectively and safely. Following a set plan also fosters communication and collaboration between development, QA, and operations teams—crucial to a successful rollout.

Let’s understand how this process typically works.

1. Choose a feature flag management system: Select a feature flag management tool or framework that fits your technology stack. These tools provide user interfaces and APIs for managing feature flags efficiently.
   
2. Identify the features to flag: Determine which features or code segments you want to control. It could be a new user interface, a specific functionality, or a backend service.
3. Set up feature flags: Set up the feature flags using your feature flag management system. Define rules for when the feature should be enabled, such as percentage rollouts, user roles, or other conditions.
4. Test in staging environment: Test the flagged features in an environment that mimics the production setup. This helps you see any problems that could happen in a real-world scenario.
   
5. Gradual rollout: Once confident about the feature’s stability, gradually roll it out to a small percentage of users. Monitor the system to detect any unexpected behavior or performance issues.
6. Collect feedback: Encourage users with access to the new feature to give feedback. Use analytics and surveys to understand how they interact with the feature and whether they achieve the desired outcomes.
7. Full rollout or iteration: Based on the user feedback and system performance, decide whether to enable the feature for all users or work on it further.
8. Monitor and maintain: Continuously monitor the features controlled by feature flags. Track usage patterns, errors, and feedback even after fully launching the feature. Ongoing monitoring helps you address issues promptly and make better choices for future development.

By following these best practices, you can use feature flags to enhance your software development process, minimize risks, and achieve agility and control in your deployments.

Plan ahead

Have a clear strategy for using feature flags. Understand the goals of each flagged feature and how it aligns with your overall product strategy.

Whether testing new functionality or gradually rolling out a feature, having a plan and objectives helps guide the implementation process.

Keep flags simple

Try to create only a few feature flags. Ensure the amount is manageable to avoid confusion and a too-complex codebase.

Make things simpler by using descriptive names for your flags. This helps developers understand the flag’s purpose without going deep into the code.

Use version control

Storing your feature flag configurations in version control systems is an effective practice. This means you can track flag changes, making it easier to understand the historical context.

Apply access control

Only some team members need the same level of access to feature flags. It’s important to decide what roles are able to change and manage these flags. Regularly review this as the company evolves. Audit access logs to ensure only authorized personnel make adjustments.

Do regular cleanups

Regularly review existing feature flags, removing flags that are no longer relevant or in use to avoid clutter.

You can implement an automated process for this task, which involves cleaning up flags based on usage metrics.

Selecting the right feature flagging platform is essential for seamless software development. It ensures smooth launches and effective feature management, making your development journey a breeze.

The following are some things to consider when choosing a platform.

• Know your needs: Clearly understand what features you require, such as A/B testing or gradual rollouts. Clarify your goals for feature flagging to align with the platform’s capabilities.
• Check the features: Look for an intuitive interface and user-friendly design. Ensure the platform offers control over features and integrates well with your existing tools and frameworks.
• Reliability matters: Prioritize platforms with a proven track record of reliability, especially during high-traffic periods. Consider uptime and performance metrics to guarantee a smooth operation.
• Security and support: Choose platforms with robust security measures, including data encryption and access controls. Emphasize excellent customer support and clear, comprehensive documentation for troubleshooting and guidance.
• Budget wisely: Understand the pricing structure, including potential extra costs. Before committing, look for trial options or free tiers to test the platform’s functionality and performance.

Feature flags are crucial to fearless innovation, allowing developers to experiment, iterate, and deliver seamless user experiences.

By integrating feature flags into your development, you’re not just coding: you’re crafting engaging and user-centric journeys that capture audiences and lead your product to success.

Amplitude is the tool to guide you through this adventure. Experimentation capabilities enable you to try out, learn, and release new features in just a few clicks. It provides the analytical backbone to complement your feature flag deployment.

You can make the most of your applications, elevate user satisfaction, and remain competitive by harnessing the combined power of feature flags and Amplitude.

Ready to level up your approach? Embrace Amplitude and empower your development endeavors when you sign up today.