Toggle is a switch that has two positions, on or off. A toggle is also a type of control in computer software that enables users to turn functions on or off, such as the toggles on the Caps Lock and Num Lock keys.

Toggles are the preferred control to use for changing system settings or preferences, such as Airplane Mode. They take up less screen estate than a pair of radio buttons, and they have a pre-selected default state (ON or OFF). Toggles are particularly useful on mobile devices where space is at a premium.

When creating a toggle switch, it is important to choose colors that provide clear visibility of the current state. Avoid using colors that can be mistaken for other meanings, such as red for ON and blue for OFF. Also consider societal and cultural differences in how color is perceived. It is best to use high-contrast colors for states and include an identifier (e.g., an icon or word) next to the toggle to reinforce its purpose and help users remember which state it is in.

Managing toggle configuration through static files becomes cumbersome as you scale up, especially when teams want to modify the toggle configuration at runtime for tests like Experiment Toggles. To reduce the need for manual modification and ensure consistency across all environments it’s good to build out some form of centralized configuration system or a dynamic override endpoint. This will enable your team to perform rapid in-memory re-configuration of specific service instances without having to restart their automated test scripts or worse, re-deploy the feature flag artifact into the testing environment.