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Segment schema reference

Read time: 3 minutes
Last edited: May 01, 2024


This topic explains the different event kinds for Segment Data Export destinations. The JSON schemas for Segment are formatted differently than LaunchDarkly's. The index, identify, and summary event kinds are not available in Segment Data Export destinations, and other events are exported with different labels.

To learn more about the Segment destination, read Segment's documentation.

There are four different event kinds exported to Segment. They are:

  • Feature events: This event is emitted when a feature flag is evaluated.
  • Click events: This event is emitted when an end user clicks on a CSS selector for which they have configured a metric in an experiment.
  • Page view events: This event is emitted when an end user loads a page associated with an experiment metrics.
  • Custom events: This event is emitted when LaunchDarkly SDK sends a custom event.

LaunchDarkly no longer supports alias events for SDKs upgraded to contexts. LaunchDarkly continues to support sending and receiving alias events for older SDK versions. For a list of SDKs that still support alias events, read Aliasing users.

Additional properties

Segment events include additional information about different LaunchDarkly properties. These properties are included in all event kinds.

These properties are:

Property nameProperty details

The event kind. This field maps onto Segment's event field.

environmentThe LaunchDarkly environment ID, also called the client-side ID, corresponding to the event.
projectThe LaunchDarkly project ID corresponding to the event.

The flag key corresponding to the event. In the case of Experimentation events, this will be the metric key for the experiment.


The key of the user object associated with the emitted event. For example, in client-side SDKs, this is the key of the currently identified user. This field maps onto Segment's userId field.

Feature events

This table explains feature event properties:

Property nameDescription
valueThe value of the evaluated flag.
flagVersionThe version of the evaluated flag.

true if this flag evaluation was allocated to an experiment.
To learn more, read Allocating experiment audiences](/home/experimentation/allocation).


The evaluation reason for the flag.
To learn more, read Evaluation reasons.


Set to another flag’s key if this flag evaluation was only performed in order to determine whether the prerequisite values were met for the indicated flag.
To learn more, read Flag prerequisites.

defaultIndicates whether the flag value was the result of the default variation being evaluated.

The variation of the flag requested. The SDK stores flag variation values in an array. This value corresponds to the index of the variation the array. Boolean flags show as 0 or 1 for true and false. For other flags, the array index starts at 0 for their different variations.


The evaluated variation's name, if it exists. If the evaluated variation doesn't have a name, this field doesn't appear.

Click events

This table explains click event properties:

Property nameDescription
urlThe URL from which a user context triggered a flag evaluation.

The CSS selector corresponding to the click event.

Page view events

This table explains page view event properties:

Property nameDescription
urlThe URL from which a user context triggered a flag evaluation.

Custom events

Custom events contain the properties listed under Additional properties.

This table explains custom event properties not listed in that section:

Property nameDescription

The numeric value of a metric if it is specified in the event. If no metric value was provided, this field doesn't appear.