A toggle is a user interface component that lets people update their preferences, settings or state of content. When used well, it’s a simple, powerful and straightforward tool. Toggles work best when users can choose between two opposing states that affect content or view. Toggle switches should be direct, use standard visual design, and deliver immediate results. They should also be able to be managed without the need to open a new window or click other buttons, and be used consistently across pages to avoid cognitive overload.

When used poorly, toggles can be confusing for users and a nightmare to debug weeks or months down the road. A common trap is using a toggle to support both existing and future behavior in the same page, which can result in confusing users with unexpected changes. To avoid this trap, be sure to use a clear and consistent label for each toggle. Also, don’t rely on color alone to convey state because not everyone sees the same colors in the same way and a toggle switch that relies solely on red for the on position will be counterintuitive to some users.

Managing toggle configuration via static files can become cumbersome once you reach a certain scale, making it hard to maintain consistency across a fleet of servers. To address this, many teams opt to move their feature flags into some type of centralized store, often an existing application DB. This usually requires building out some form of admin UI to allow system operators, testers and product managers to view and modify their toggle configuration.