Feature Flag Best Practices: Lessons from Production

Feature flags are deceptively simple. A boolean that shows or hides functionality. But at scale, poor flag management leads to technical debt, bugs, and confusion. Here's what we've learned.

Naming Conventions Matter

A flag named flag1 tells you nothing. Six months later, nobody knows what it does or if it's safe to remove.

Use a Consistent Pattern

Examples:

• checkout-new-payment-flow
• api-rate-limit-v2
• dashboard-dark-mode
• experiment-pricing-page-b

Flag Types and Lifecycles

Not all flags are created equal. Understanding the type helps determine how long it should live.

The Flag Cleanup Problem

Technical debt from stale flags is real. Every flag is a branch in your code. Old flags create confusion, increase cognitive load, and can cause bugs when someone changes the "wrong" path.

Best Practices for Cleanup

• Set expiration dates - When creating a release flag, schedule its removal
• Track flag age - Flags older than 30 days should be reviewed
• Monitor usage - If a flag hasn't been evaluated in weeks, it's probably dead code
• Make removal easy - Include flag location in metadata so cleanup is fast

Targeting Strategies

Start Small, Then Expand

The safest rollout pattern:

1. Enable for yourself / the team
2. Enable for internal users / dogfooding
3. Enable for beta users / early adopters
4. Roll out to 1%, 5%, 25%, 50%, 100%

Use Segments, Not Individual Users

Targeting individual user IDs doesn't scale. Instead, define segments:

• beta-users - Users who opted into beta
• enterprise - Customers on enterprise plans
• internal - Employees

Anti-Patterns to Avoid

Summary

Feature flags are a powerful tool when used correctly:

• Use clear, descriptive names
• Know your flag types and plan for their lifecycle
• Clean up flags aggressively
• Use segments for targeting
• Avoid anti-patterns that create debt