Flag deliveries

Using a feature flag delivery, you can:

Deploy a flag to a percentage of your user traffic.
Roll the flag back if needed.
Target your delivery to custom audiences so that only a subset of users (for example, users in Spain) gets access to the flag.

Deliveries take effect immediately without a new code deployment. All of this functionality is available with microsecond performance impact via free (see plans for advanced features), easy-to-use, open source SDKs.

Flag deliveries are a type of flag rule, as are A/B tests. The following table compares A/B tests and flag deliveries:

	Experiment	Flag Delivery
Purpose	Lets you gather metrics data so you can compare multiple flag variations.	Lets you deploy a flag that you've already tested or measured some other way, such as qualitative feedback.
User impressions	When a user is assigned to an experiment, Optimizely sends a decision event so that information is recorded in your test results.	When a user is assigned to a delivery, Optimizely does not send a decision event. This means that extra network traffic and test results aren't generated.
Variations	Test multiple variations—on versus off or a multivariate test of different configurations. You can create one experiment per flag.	Each delivery exposes users to one variation. You can have multiple deliveries per flag.
Started by	Decide method	Decide method

Advantages of using flag deliveries

Flag deliveries help you mitigate risk. For example, if you want to be sure that a new feature doesn’t degrade the visitor experience, start by launching the feature flag to a small percentage of visitors, then increase. Decrease the percentage exposed to the flag if you encounter problems with the new feature.

Deliveries also let you launch winning flag variations that you identify through experimentation. After you find a winning variation, use a delivery to gradually expose the variation to your visitors in a controlled fashion.

Deliver to multiple audiences

Often, you want to deliver more strategically than to a random percent of your total user base. You can use audiences to do so. For more information, see Target audiences.

Here are some examples of how to use multiple audiences to deliver flags:

Deliver sequentially to different user bases

First, you gradually deliver or roll out a new feature flag to beta users. Second, you retain the beta user delivery at 100% and roll out to your lowest-value customers. Finally, you roll out the flag for your highest-value customers.