A toggle is a switch that can be moved between two positions, like on and off. Toggles can be found in many everyday technology devices such as phones and laptops. Toggles are also used in software applications to enable or disable features. A toggle can be configured to respond to a variety of conditions including fitness test results, settings in a feature management system, or a value provided by a config file.

Some toggles will only live for a few days or weeks (Release Toggles) whereas others like Permissioning Toggles will live longer, sometimes permanently. For these longer-lived toggles it’s important that the toggling decision is made on a request-by-request basis which requires a dynamic flag.

Toggle configuration can be hardcoded directly into the codebase in various ways. While this method has its benefits it becomes cumbersome at scale and can be difficult to manage. In most cases a better solution is to move the toggle configuration into some type of centralized store, often an existing application DB. This will allow system operators, testers and product managers to easily view and modify toggle configuration.

The color used to indicate an active toggle can have a large impact on its perceived state. As guidance from WCAG suggests, designers should not rely solely on color to communicate meaning and should always consider the use of other visual clues. In the case of toggles it’s important to note that a significant portion of the population has red/green color blindness so using green as an on/off signal is not going to be helpful for these users.