Track user events

Experiments let you track how users react to different variations. To measure the relative success of your experiment, you must tell Optimizely which eventsevents to track. After Optimizely aggregates enough events to produce meaningful metrics, you can evaluate your flag variations on the Experiment Results pageExperiment Results page.

As part of designing your experiment, you decide which tracked events to use as metrics. Events that track a desired user action, like a purchase, signup, or form submission, are called conversion events. They can capture anything from simple clicks and page views to purchases and scroll depth. In general, you want to track events closely associated with the user experience your experiments are updating. See How Optimizely counts conversionsHow Optimizely counts conversions.

Event properties let you attach additional information to an event. For example, you can add information about a product or action performed to create a more specific metric on the Experiment Results page.

Optimizely supports event properties as a nested object within event tagsevent tags. When you call the track event method, you can include event tags as an optional key-value argument. To send event properties, use the reserved key $opt_event_properties as a nested key within the tags object.

Go to Example code for implementation examples, Create eventsCreate events for configuration instructions, and Create a metric using the metric builderCreate a metric using the metric builder for guidance on adding event properties to metrics.

At a high level, complete the following steps to track events:

You can track events on the server and client using an SDK or the Agent. You can also track events using the Events APIEvents API if you do not have an SDK implemented. For information, see Track across platformsTrack across platforms.

The following Swift example shows how to call the track event method, including optional user attributes.

For the other SDKs, refer to the corresponding reference guides.

For Optimizely Agent, see Use Optimizely AgentUse Optimizely Agent.

You can track events using the SDKs or, for more advanced or offline use cases, an HTTP-based integration.

Use one of the following options:

SDKs provide the following benefits:

For example, use a server-side SDK (such as Python, Java, or Node) to make experiment decisions and a client-side SDK (such as JavaScript, React, iOS, or Android) to track user behavior.

If you use multiple SDKs within the same project, ensure they share the same datafile and user identifiers. For guidance, see Multiple SDK implementationsMultiple SDK implementations.

On the Experiment Results page, you can track nonbinary metrics such as revenue or other numeric values. For information on using reserved event tags to track nonbinary metrics, see Tag eventsTag events.

After you Create eventsCreate events, complete the following:

For information on how Optimizely handles events, see Events: Track clicks, page views, and other visitor actionsEvents: Track clicks, page views, and other visitor actions.

Also, see how Optimizely attributes a single user's events over timehow Optimizely attributes a single user's events over time.