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

# List randomizers

> A study's randomizers (weighted split tests) with their arms

Returns every randomizer in a study. A randomizer routes each participant to exactly one arm; an arm shows one question or one question group. Groups owned by an arm also carry that arm's id as `routing_branch_id` in the question-groups endpoints.

<ParamField query="study_id" type="string" required>The study ID.</ParamField>

### Response

An array of randomizers.

<ResponseField name="id" type="string">The randomizer ID.</ResponseField>
<ResponseField name="name" type="string">Internal name; never shown to participants.</ResponseField>
<ResponseField name="parent_question_group_id" type="string | null">The group the randomizer sits in, or `null` at the top level.</ResponseField>
<ResponseField name="display_order" type="integer">Position among its siblings.</ResponseField>

<ResponseField name="arms" type="array">
  In arm order. Each arm has `id`, `label`, `weight_basis_points`, `display_order`, and exactly one of `question_id` or `question_group_id` (both `null` for an empty placeholder arm).
</ResponseField>

<RequestExample>
  ```bash cURL theme={null}
  curl "https://api.getversive.com/api/v1/randomizers?study_id=9b2f7c1e-4a4b-4f6e-9a1d-1c2d3e4f5a6b" \
    -H "Authorization: Bearer $VERSIVE_API_KEY"
  ```
</RequestExample>

<ResponseExample>
  ```json 200 theme={null}
  [
    {
      "id": "5f1c2d3e-0000-4000-8000-000000000001",
      "study_id": "9b2f7c1e-4a4b-4f6e-9a1d-1c2d3e4f5a6b",
      "name": "Concept test",
      "parent_question_group_id": null,
      "display_order": 2,
      "arms": [
        {
          "id": "7a0b1c2d-0000-4000-8000-000000000001",
          "label": "Concept A",
          "weight_basis_points": 5000,
          "display_order": 0,
          "question_id": "c1d2e3f4-0000-4000-8000-000000000001",
          "question_group_id": null
        },
        {
          "id": "7a0b1c2d-0000-4000-8000-000000000002",
          "label": "Concept B",
          "weight_basis_points": 5000,
          "display_order": 1,
          "question_id": null,
          "question_group_id": "d4e5f6a7-0000-4000-8000-000000000002"
        }
      ]
    }
  ]
  ```
</ResponseExample>