Build vs Buy: You Don't Need Another Side Project

When you first need feature flags in a .NET application, the answer is wonderfully boring. Install Microsoft.FeatureManagement, put some flags in appsettings.json, and you're off to the races. Microsoft's library handles the feature evaluation plumbing, filters, targeting, and integration with ASP.NET Core. And honestly? That works great.

For a small application with a handful of flags, you probably don't need anything more. Then things grow. Suddenly your appSettings.json has become a feature management database with worse UX.

When Configuration Becomes a Product

The problem isn't evaluating a flag. That's easy. The problem is everything around it. What if a product manager wants to enable a feature without asking a developer? What if you want to change a flag without rebuilding and redeploying the application? What if you have multiple environments and enough flags that nobody remembers which configuration file is currently lying to them?

At that point, you're not really managing configuration anymore. You're building a feature flag platform. And that's where the build-vs-buy question gets interesting. AI makes rolling your own much easier than it used to be. Simple feature flag platforms can absolutely be built cheaply, but requirements like management interfaces, high availability, and distributed rollouts make the problem considerably less trivial.

But AI Makes Building It Easy... Right?

Well, yes. AI has made generating code dramatically cheaper. You can ask an AI to build a feature flag API, admin UI, database schema, and SDK before your coffee gets cold. Congratulations. You have something that works. You have not eliminated:

  • Maintenance and security updates
  • Hosting and other infra costs
  • Backups
  • Monitoring
  • Documentation
  • Support and On-call
  • Future-you wondering why past-you volunteered for this

AI reduces the cost of writing code. It doesn't necessarily reduce the cost of owning software. That's an important distinction.

Build vs Buy Isn't About Code

The real question isn't:

"Can I build this?"

Of course you can. The question is:

"Do I want to keep building and maintaining this?"

For a simple app with a few flags, build it. For a growing application where non-technical people need to safely manage features without touching JSON files or deployment pipelines, that's where a focused third-party solution like FeatureFlags.app comes in. It gives your team a proper place to manage feature flags while they stay focused on what's really important. Build your product. Buy the plumbing.

Your developers will thank you. Probably.