Toggle is a user interface element that allows users to update preferences, settings, and other types of information. They are a preferred control for mobile devices because they take up less space than two radio buttons. Because toggles enforce a mutually exclusive state of on or off, they can be used to quickly implement and test new functionality with a small set of users.

While they may be easier to code than radio buttons, toggles can cause cognitive issues if used poorly. Inconsistent visual cues can confuse users, as can low-contrast colors (like green and red) that do not indicate change of state. Additionally, using the word “on” in the toggle label can be confusing for some users due to cultural and societal implications. To avoid these issues, use clear labels that describe what the toggle will do when pressed and include a color indicator for current state. In addition, be sure to use a high-contrast color for the toggle state and evaluate the societal and cultural impacts of your choice.

Savvy teams consider Feature Toggles as inventory that comes with a carrying cost and seek to keep that inventory low. To this end they usually add a task to their backlog to remove toggles as soon as they are no longer needed. They also often build out some form of centralized UI to manage toggle configuration in lieu of static files which can become cumbersome at scale. At the very least a team should always test the production toggle configuration with all toggles flipped On and the fall-back configuration with all toggles flipped Off.