A toggle is a switch that has two possible states, on and off. They’re found in most software and hardware devices where there are options menus.

A Togle is a good control when you want to change the state of system settings or preferences. They take less screen estate than two radio buttons and allow users to toggle between a default value and a specific setting without requiring them to press a button.

Toggle configuration can be managed in a number of ways but the most common and recommended approach is static files. The downside to this approach is that it can be relatively fiddly, particularly when the number of toggles grows, and ensuring consistency across multiple servers becomes an issue.

Many organizations prefer to have a centralized feature flag store where they can manage toggle configuration rather than using static files. This makes it easier to roll out toggle configuration changes on a consistent basis as we’re not needing to edit individual files every time we change the state of a feature toggle.

Another advantage of storing toggle configuration in a centralized system is that it allows us to quickly see the current state of all toggles when we’re building a release, and can quickly roll out a new release without needing to change any of the toggles if their toggling decisions have changed or are expected to change.

Using feature toggles can be a great way to test features and their behaviors before releasing them into production. However, it’s important to keep in mind that it’s not always practical to test a feature with every toggle in the configuration. It’s often preferable to only test the toggle configuration which you expect to be flipped On in the release and to run fall-back tests where those toggles are flipped Off too.