[mattbrewsbytes]

I've built one in a few minutes, not hours. Our main requirement was releasing tested code to production ahead of when other interacting pieces are ready (other API's, UI changes, etc.) Usually there is an API contract in place with the other party at this point and feature flags help a CI/CD process keep things moving instead of sitting on a feature.

In Rails if you have Active Admin, you just define the migration for feature flags and you are basically done. AA gives you a UI which you can protect with roles. Put a couple methods on the model and then you can toggle features anywhere in your code.

Our use case is very small, feature flags get deleted after all the moving parts are shipped and working. I'm sure your product has many more use cases and capabilities.