If you're looking for a service to support dynamic feature toggles (and bear in mind that simple feature toggles work well too), check out ConfigCat. We'd describe it as "like LaunchDarkly but cheaper and a bit less fancy" and find that it does most of what we need. ConfigCat supports simple feature toggles, user segmentation, and A/B testing and has a generous free tier for low-volume use cases or those just starting out.