Flagship.io - Feature Flag as a Service - Separate code deployments from feature releases to speed up development cycles, mitigate risks and release safely.

ConfigCat - ConfigCat is a developer-centric feature flag service with unlimited team size, awesome support, and a reasonable price tag.

Split.io - In a world where product development teams are pressured to do more with less, Split’s Feature Data Platform™ gives you the confidence to move fast without breaking things.

Flagsmith - Flagsmith lets you manage feature flags and remote config across web, mobile and server side applications. Deliver true Continuous Integration. Get builds out faster. Control who has access to new features. We're Open Source.

LaunchDarkly - LaunchDarkly is a powerful development tool which allows software developers to roll out updates and new features.

Unleash - Open source Feature toggle/flag service. Helps developers decrease their time-to-market and to increase learning through experimentation.