A toggle is a switch that allows you to alternate between two or more states or options. It is commonly used in technology, computing, and programming to provide users with a way to select from different settings or modes of operation.

The word toggle derives from the 18th century term “pin passed through the eye of a rope” to fasten it. Today, it’s more common to use the term to refer to a mechanical or computer-related fastener that can be operated by the push of a button or the stroke of a key.

For software engineers, a toggle is a type of feature flag that can be flipped on and off to enable or disable functionality without requiring code deployment. Unlike traditional feature branches, feature toggles can be activated and deactivated at any time, allowing teams to experiment with new features in production before committing them to the master branch. This can help reduce risk and improve overall software quality.

Typically, feature toggles are used in conjunction with a Kanban flow to support dev teams as they write new features. They are often referred to as “Feature Toggles” but can also be called “Flags”. In the context of Kanban, they are used to manage both the scope and release schedule of a feature. Toggles can be used to enable or disable a feature based on a variety of conditions including fitness test results, feature management software settings, or a variety of other variables.

Many teams choose to manage their feature toggle configuration in some form of centralized database. This allows system operators, testers and product managers to see and modify the toggle configuration across all servers in a fleet. Often times this is accomplished by using an existing application DB or by building out some form of admin UI for managing features and their toggle configuration.

Toggle Configuration Management

Once a team has decided to implement a toggle it is important that they test all the possible configurations before releasing them to production. It’s common practice for teams to test a fallback configuration where any toggles they intend to release are flipped Off and any existing or legacy behavior is enabled. It’s also a good idea to perform some tests where all toggles are flipped On, to avoid any unexpected regressions.

Managing a large number of toggles can become cumbersome when done manually via static files. To address this problem, many organizations will move their toggle configuration into some type of centralized store, often an existing application DB. This approach is usually accompanied by the build-out of some form of admin UI which will allow system operators, testers and product managers to view and modify the toggle configuration across all servers in their fleet.

Permissioning Toggles are very similar to Champagne Brunch in that they can be triggered on demand and are used to enable or disable user-specific features. However, because they are triggered on a request-by-request basis they tend to be shorter lived than other categories of Feature Toggles.