A toggle is a switch that allows users to manage the state of something, usually a view. It’s a good control when you need to allow people to update their preferences or settings because it’s more visually compact than a radio button and can take on the form of a checkbox if necessary. However, toggles are best for binary actions that happen immediately after a user “flips the switch”. For anything else, consider using a different control like a slider or list.

Toggles are transitionary by nature and should stay in the code for only a short period of time before being replaced with a new one. This practice is known as blue-green deployment. This prevents any problems from affecting the whole system by limiting the scope of impact for each release.

When designing your toggles, use high-contrast colors to make it clear which one is active. It’s also helpful to have a secondary visual cue, such as a bold-thin combination. Embossment is another good option, but it proved unreliable as a sole signifier since it can be hard to discern at small sizes. Finally, be sure to evaluate the societal and cultural implications of your choice for color.

Toggle configuration is often stored in static files, but this can become cumbersome at scale and is hard to maintain consistently. For these reasons, many organizations move toggle configuration into some type of centralized store, like an existing application DB or admin UI. This makes it easier to track and maintain consistent toggle configuration across a fleet of servers and provide product managers and testers with easy access to feature flags.