What Is a Toggle?

A toggle (or toggle) is a switch that turns something on or off. You can find them in hardware like the caps lock and num lock keys on a keyboard, as well as software such as options menus that provide users with the ability to select between a variety of settings and preferences.

While they can be incredibly useful tools to help a team manage the complexity of a product, the use of Toggles must be done with great care. A toggle can have a negative impact on performance and usability if it’s not implemented correctly. Toggles must be clearly labeled and positioned in a way that is intuitive for the user to understand what their effect will be. Toggle switches should be shaped like sliders to help them convey the idea of on/off states, and they should utilize visual cues such as movement and color to signal when their state has changed. Toggle switches should be used sparingly and should always be accompanied by a clear description of their effect on the application’s behavior.

Savvy teams view the Toggle inventory within their codebase as a kind of carrying cost, and they seek to keep that inventory as low as possible. This is why it is important to have a system in place that makes it easy for a developer to add new Toggle configurations and then to remove those Toggles as they become irrelevant. Some teams have even gone as far as to create “expiration dates” on their toggles so that a test will fail when it attempts to run against an out-of-date configuration.

If a company’s toggle configuration management is only done through static files it can be very difficult to make changes to the configuration at scale. In order to address this challenge many companies move their toggle configuration into some kind of centralized store, often an existing application DB. This often accompanies the build-out of some type of admin UI that allows product managers and testers to see and modify feature flag configuration.

Toggles are commonly used in A/B testing as a method of making incremental improvements to the user experience. When configured properly Experiment Toggles allow for the consistent delivery of a single codepath to different cohorts, providing a way to compare the effects of those paths on user metrics such as purchase conversion rate or Call To Action click through rates. Toggle Routers are also often used to perform more complicated AB tests such as multivariate testing, where multiple variants of the same page layout or functionality are exposed to each user at runtime and then tracked for their effectiveness against key metrics.