> ## Documentation Index
> Fetch the complete documentation index at: https://docs.nebuly.com/llms.txt
> Use this file to discover all available pages before exploring further.

# AB Testing: Add User to Experiment

Add a user to an existing A/B testing experiment.

### Body

<ParamField body="user" type="string" required>
  The identifier of the user to add to the experiment
</ParamField>

<ParamField body="experiment_flag_name" type="string" required>
  The unique flag name assigned to the experiment
</ParamField>

<ParamField body="assignment_probability" type="number">
  The sampling rate for assigning users to the experiment (between 0 and 1). If not provided, the sample rate specified in the UI will be used. Set to 1 to assign all new users to the experiment.
</ParamField>

### Response

<ResponseField name="success" type="boolean">
  Indicates if the user was successfully added to the experiment
</ResponseField>