Feature flag lifecycle: Development to deprecation

Feature flags promise a world where you can ship code whenever you want and control who sees what. But here's the thing - without proper lifecycle management, they quickly turn into a mess of forgotten toggles and confusing conditionals that nobody wants to touch.

I've seen codebases with hundreds of flags where developers are afraid to remove anything because they don't know what might break. The good news? Managing feature flags doesn't have to be complicated if you follow a clear lifecycle from creation to retirement.

Introduction to feature flags and their lifecycle

let you control features without changing code - you just flip a switch and boom, the feature's on or off. They're basically conditional statements that check whether to show Feature A or Feature B (or nothing at all) based on whatever rules you set up. This makes them perfect for where you're constantly shipping new stuff.

Every flag goes through a predictable journey. You create it (usually defaulted to "off"), test it with a small group, gradually roll it out to more users, then eventually remove it once the feature is stable. That last part - the removal - is where most teams drop the ball.

The problem is that flags accumulate like old cables in your drawer. Without proper and , you end up with a codebase littered with if-statements checking flags that haven't changed in years. I've worked with teams who discovered flags from features that were two years ago still sitting in production. It's not just messy - it's a maintenance nightmare that slows down every future change.

Best practices for creating and implementing feature flags

Start with naming. You'd be surprised how many incidents stem from developers not understanding what exp_v2_final_FINAL_really actually controls. The team at DraftKings learned this the hard way and now enforces standardized naming conventions across all their flags. Something like checkout_new_payment_flow beats test_flag_123 every single time.

Always introduce flags in their "off" state. This gives you a safety net - if something goes wrong during deployment, at least the new (potentially broken) code path isn't active. Document everything while it's fresh in your mind: who owns this flag, what it does, when it should be removed. Trust me, Future You will thank Present You for taking those five extra minutes.

Before you flip that switch, you need three things:

• A risk assessment (what could go wrong?)

• Clear KPIs to monitor (how will you know if it's working?)

• An actual rollout plan (not just "we'll turn it on and see")

Treat flag changes like production deployments because that's exactly what they are. Get the same approvals, follow the same process, take it just as seriously.

Here's what works for keeping things clean: create the cleanup ticket when you create the flag. Statsig's approach involves setting up automated reminders that bug you about stale flags - either through CI failures or Slack messages. It's annoying in the best way possible because it forces you to deal with flag debt before it piles up.

Managing feature flags during testing and rollout

Never, ever activate a flag without first. I don't care if it's "just a small change" - that's what everyone says before they break production. Spin up a staging environment, flip the flag, and make sure both the "on" and "off" states work as expected.

Once you go live, watch your metrics like a hawk. Set up dashboards for whatever matters to your feature - conversion rates, error logs, performance metrics, user complaints. The beauty of flags is that if something goes sideways, you can turn it off instantly. But you have to be watching to know when to pull that trigger.

Your should look something like this:

1. Internal team only (eat your own dogfood)

2. Beta users or a small percentage of traffic

3. Gradual increase to 50%, then 100%

4. Monitor at each stage before proceeding

The isn't just about turning things on - it's about knowing when to turn them off and remove them entirely. Schedule regular reviews (monthly works well) where you go through active flags and ask: "Can we yet?" If a flag has been at 100% for a month with no issues, it's probably time to remove the flag and just keep the new code.

Safely deprecating and removing feature flags

Deprecation is where the rubber meets the road in the feature lifecycle. You can't just yank a flag out - you need to give developers a grace period to remove references from their code. How long? Depends on your team size and deployment frequency, but two weeks to a month usually works.

Run regular audits to find zombie flags. These are the ones that nobody remembers creating, serving 100% of traffic for months, just sitting there adding complexity. Statsig and similar platforms help by tracking flag usage and sending reminders, but even a simple spreadsheet beats nothing.

Before you delete anything, make absolutely sure it's not being used. Check your codebase, check your configs, check with other teams. I once saw a team delete what they thought was an unused flag only to discover it controlled a critical feature for enterprise customers. Not fun.

The teams that succeed at lifecycle management treat flags as temporary by default. They:

• Create cleanup tickets immediately when adding flags

• Maintain a dashboard showing flag age and usage

• Review flag changes just like any other code change

• Set expiration dates and stick to them

Think of feature flags as scaffolding - useful while you're building, but you wouldn't leave it up forever. By building cleanup into your process from day one, you get all the benefits of continuous delivery without drowning in technical debt.

Closing thoughts

Feature flags are incredibly powerful, but they're not fire-and-forget. The teams that get the most value from them are the ones who manage the entire lifecycle - from thoughtful creation through careful rollout to timely cleanup. It takes discipline, but the payoff is huge: safer deployments, faster iteration, and a codebase that doesn't make developers cry.

Want to dive deeper? Check out Martin Fowler's comprehensive guide on feature toggles, or explore how platforms like Statsig can automate much of the lifecycle management for you. And if you're dealing with an existing mess of flags, start small - pick the five oldest ones and clean them up this sprint.

Hope you find this useful!