Using Feature Flags to Control Free Delivery Banner Visibility

Continuing the previous e‑commerce case study, the company wants to offer a “free delivery” service to a specific group of customers and control its exposure via a feature switch.

Marketing managers aim to heavily promote the “free delivery” feature and plan to place a banner at the top of the homepage.

However, they do not want the banner shown to users who are not eligible for free delivery, to avoid angry customers.

Therefore, a feature switch must control when and to whom the banner is displayed.

A new feature flag called “free-delivery-banner” can be created to manage the banner’s visibility, ensuring that when the “free‑delivery” flag is turned off, the banner is also hidden.

Some feature‑flag management systems link flags together, allowing one flag to depend on another, but a simpler solution is to use a single flag to control both the core feature and its related banner.

While this seems like a best practice, grouping flags by team can complicate matters, especially when the team handling “shipping‑cost calculation” is not closely related to the team implementing the “free‑delivery banner”.

Ideally, product delivery teams should be organized around product features (e.g., product detail page team, search team, homepage team) rather than by technical specialty or project, reducing the number of cross‑team feature flags needed.

Some features inevitably require changes across multiple teams; in such cases, a shared flag can be used, but each flag should still belong to a clearly responsible team that drives rollout and monitors performance.