How to build an in-house feature-flag system?

Building an in-house feature flag system offers control and customization but can become challenging as complexity grows, especially for tasks like gradual rollouts and cross-team collaboration. Initial methods such as using environment variables are simple yet limited, requiring redeployment for changes and lacking user-level targeting. Storing values in a database improves personalization without redeployment but still demands technical intervention and is inefficient for global flags. Developing a user interface democratizes flag management across teams but remains limited in complex targeting capabilities. Advanced needs like random traffic splitting for A/B testing add further complexity, necessitating a robust internal framework to manage user segmentation and maintain consistency. For sophisticated requirements, third-party providers like Tggl offer comprehensive solutions with advanced targeting, collaboration tools, and technical debt management, allowing teams to concentrate on product development rather than the intricacies of feature flagging systems. Deciding between an in-house and third-party solution depends on the specific needs and maturity of the product, with DIY fitting simple scenarios and third-party options being more suitable as demands grow.