Cleaning Up Feature Flags: The Art of Not Leaving a Mess

You said you'd remove that flag after launch. You lied. It's been six months and the flag is still in appsettings.json , the if statement is still in your controller, and nobody remembers which state is "on." This is how codebases turn into haunted houses. Why Cleanup Matters Dead feature flags are technical debt with teeth . They add branches to your code that nobody tests. They confuse new developers who don't know the history. They inflate configuration files and make deployments harder to reason about. And they compound. Every flag you don't clean up makes the next cleanup harder because the cognitive load of understanding the system keeps increasing. The cost of removing a flag is lowest immediately after the feature ships, while everyone still remembers what the thing does. Six months later? Good luck. Track Every Flag You can't clean up what you can't find. Maintain a registry of every active feature flag with: Name Purpose Owner Date created Expected removal date This can be a spreadsheet, an issue tracker, internal documentation, or a dedicated feature flag management system. The format doesn't matter nearly as much as the habit. When you add a flag, add it to the registry. When you remove a flag, remove it from the registry. If your registry contains flags with no owner or no removal date, congratulations: you've found your next cleanup project. Set Expiry Dates Every flag should have a planned removal date when it's created. For example: Release toggles: Remove shortly after the feature ships. Two weeks is a reasonable default. Experiment toggles: Remove when the experiment concludes. Ops toggles: May be permanent by design. Permission toggles: May also be permanent, but document that explicitly. If a flag has been alive longer than its planned expiry and nobody deliberately extended it, it's already a zombie. Treat it accordingly. Make Cleanup Part of the Process Flag cleanup doesn't happen unless someone owns it. Add a cleanup step to your feature compl