Feature Flags Gone Wild

Introduction: When Flexibility Breaks Things

Feature flags are supposed to help. Roll out code safely. Test in production. Change things without redeploying. All good stuff.

But when no one’s watching, those same flags can quietly wreck your product. They turn into clutter. Confuse your team. Slow things down. That’s when flexibility starts feeling fragile.

This piece dives into what goes wrong when feature flag hygiene goes out the window—real stories, real costs, and hard-earned lessons.

What Is Toggle Drift?

Toggle drift happens when feature flags don’t behave the way you thought they would. It usually shows up when:

• Flags stay on (or off) for the wrong users.
• Old flags stick around long after a feature goes live.
• No one remembers why a flag exists—or what it’s even doing.

The result?

• Bugs that are nearly impossible to track down.
• Users getting different versions of your app.
• A growing mess that slows your team down.

Case Study 1: ShopSavvy’s $250,000 Flag Fail

ShopSavvy, a mid-size e-commerce brand, had a slick new user profile design ready just in time for Black Friday. They used a feature flag to launch it. Sales jumped 150%. Everyone celebrated.

Until... users started complaining. Some saw the new design in dark mode. Others got the old version. Nothing made sense.

Turns out, a flag that controlled the theme had gone sideways. It was partially stuck “on” for users who’d visited before, and “off” for everyone else. A classic case of toggle drift.

Here’s what that cost them:

• Confused users and a flood of support tickets.
• Three weeks of messy debugging.
• An estimated $250,000 hit in lost revenue and support costs.

The fix? A blunt-force script to reset every user’s toggle:

# Reset inconsistent dark_mode states
for user in $(get_users); do
    toggle_status=$(get_toggle_status $user "dark_mode")
    if [ "$toggle_status" != "on" ]; then
        set_toggle_status $user "dark_mode" "off"
    fi
done

Lesson learned: feature flags don’t clean up after themselves.

Case Study 2: Streamline and the Flag Graveyard

Streamline, a startup building collaboration tools, leaned hard on feature flags. At one point, they had 15+ active flags in their codebase—many of them stale, undocumented, or forgotten.

No one owned the cleanup. Over time, things got weird.

One old flag—left over from a prototype notification feature—accidentally blocked alerts in a new tool rollout. Some users got spammed. Others got nothing. Chaos.

What happened next:

• Deadlines missed.
• Product teams left in the dark.
• A 30% churn rate among pilot users.

Their fix started with a cleanup job:

# Deprecating stale feature flags with Terraform
resource "feature_flag" "stale_flags" {
  for_each = var.stale_flags

  name        = each.key
  enabled     = false
  description = "Deprecated flag, to be removed"
}

The takeaway? Flags aren’t harmless just because they’re old. They decay. And when they do, they break things.

How to Actually Manage Feature Flags

Feature flags aren’t just “on/off” switches. They’re configuration tools. And like all config, they need structure.

Here’s what helps:

✅ Assign Owners

Every flag should have a clear owner. Someone responsible for:

• Rolling it out
• Retiring it
• Keeping it documented

📆 Set Expiration Dates

If a flag doesn’t have an end date, it’ll live forever. Don’t let that happen. Add a calendar reminder. Revisit it. Decide whether it still needs to exist.

🗂 Keep a Flag Registry

Track your active flags. Keep notes. Why it was added. Who owns it. What it controls. Make it easy to find and understand.

🧪 Monitor in Production

Know which users see what. Set up alerts if a flag is acting weird. If something feels off—it probably is.

Tools That Help Keep Things Clean

A few platforms can take the pain out of flag management:

• LaunchDarkly – Full-featured with flag targeting, auditing, and analytics.
• Unleash – Open-source, self-hostable, and dev-friendly.
• Flagsmith – Great UI and REST APIs for managing flags at scale.

These aren’t just toggle tools. They’re systems that help you stay organized and sane.

Conclusion: The Cost of Not Cleaning Up

Feature flags give you speed—but they come with strings attached. If you ignore them, they don’t just sit there. They grow into a hidden pile of tech debt.

Toggle drift and stale flags might not crash your app today. But they will chip away at your product. Quietly. Relentlessly.

So do this:

• Audit often.
• Kill flags early.
• Write things down.

Because the next time a bug shows up, the problem might not be your code—it might be hiding in your flags.