Adopt
Unleash is a feature (toggle / flag) management service written in Node.js. You can enable/disable features independent of deployment schedules. For larger projects with many feature flags you can benefit from usage statistics and metrics which are collected for each flag.
A lot of activation strategies are provided by Unleash out of the box, like Boolean On/Off, Gradual Rollout, IPs, and so on, while allowing you to add custom strategies.
To evaluate the feature flag you can choose one of the official SDKs or use the REST-API directly.