What Is a Toggle?

A toggle is a simple user interface element that changes from one state to another. They’re commonly used to change system settings and preferences. Often, the toggle will have two states: On or Off. It’s an alternative to radio buttons and checkboxes. A toggle switch allows you to control multiple features at once, which can save time and screen space. It’s also easy to update, as you can select the option and instantly see the results. When using toggles, it’s important to provide clear and direct labels, use standard visual design, and deliver immediate results. Additionally, be sure to evaluate the societal and cultural implications of your toggle color scheme, as some users may find colors to be confusing or counterintuitive.

Historically, the word toggle was defined as “a pin passed through the eye of a rope to fasten it.” While that definition remains true, today we primarily use the term for an up-and-down command such as the key on your computer that turns caps lock on and off.

We use toggles in software development as well, but in a different way. Rather than passing a pin through the eye of a rope, we pass a feature flag through an existing code path in a production application to see what effect it has on user behavior. This process is commonly referred to as A/B testing or multivariate testing and is used in many industries to make data-driven optimizations to the customer experience.

Toggle configuration is typically managed in some type of centralized storage, usually an existing application database. While this is an effective strategy it can become cumbersome to manage at a certain scale, especially if we have multiple teams managing the configuration. As a result, many organizations choose to move their toggle configuration into some type of admin UI which makes it easier for system operators, testers and product managers to modify.

It’s important to test all of the toggle configurations that will eventually go live in production, as well as all of the fallback or alternate states (i.e., toggles flipped off that will be replaced with toggles flipped on). Additionally, it’s a good idea to perform some of your tests with all toggles flipped off so that any regressions can be easily identified.

While it’s tempting to hardcode a toggle in the source code, this can be a dangerous practice. For this reason, most savvy teams adopt a best practice of adding a task to the team backlog whenever a release’s toggle configuration needs to be removed. In addition, some teams even put in place “expiration dates” for their toggles, which will fail a release or throw an error in the build process if the toggle is still active after the expiration date has expired. Ultimately, it’s all about making sure that the team has the tools they need to make informed decisions when selecting a toggle configuration to deploy into production. This is a critical step to building a quality product.