---
title: "List custom columns"
method: GET
path: "/v1/column"
tags: ["CustomColumns"]
---

# List custom columns

`GET /v1/column`

## Request

- Base URL: `https://api.braintrust.dev`
- URL: `https://api.braintrust.dev/v1/column`
- Auth: one of:
  - HTTP bearer
  - none

List the custom columns defined for a table. Requires read permission on the scoping object.

Custom columns are scoped to a specific table by the combination of `object_type`, `object_id`, `subtype`, and `variant`. Use the same scope when creating and listing columns. Use these combinations to display columns in the corresponding UI table:

| Page | `object_type` | `object_id` | `subtype` | `variant` |
| --- | --- | --- | --- | --- |
| Dataset | `dataset` | Dataset ID | `""` | `dataset` |
| Project logs | `project` | Project ID | `project_log` | `project_log` |
| Experiment details | `project` | Project ID | `experiment` | `experiment` |
| Experiments list | `project` | Project ID | `experiment` | `experiment_list` |

Experiment span columns apply across experiments in the project.

## Query parameters

- `object_type` 'organization' | 'project' | 'experiment' | 'dataset' | 'prompt' | 'prompt_session' | 'group' | 'role' | 'org_member' | 'project_log' | 'org_project' | 'org_audit_logs' | 'project_group' | 'project_group_projects' | 'ai_secret' | 'org_ai_secret' | 'org_account', required: The type of the object the custom column is scoped to, usually `project`
- `object_id` string, uuid, required: The ID of the scoping object. Use the project ID for project logs, experiment spans, and the experiments list. Use the dataset ID for dataset rows
- `subtype` union: The child object type the custom column applies to, such as `experiment` or `project_log`. Use an empty string when the column applies directly to the scoping object, such as a dataset
  - 'organization' | 'project' | 'experiment' | 'dataset' | 'prompt' | 'prompt_session' | 'group' | 'role' | 'org_member' | 'project_log' | 'org_project' | 'org_audit_logs' | 'project_group' | 'project_group_projects' | 'ai_secret' | 'org_ai_secret' | 'org_account': The object type that the ACL applies to
  - ''
- `variant` 'project' | 'experiment' | 'dataset' | 'project_log' | 'experiment_list': The table variant the custom column applies to. If omitted, defaults to the nonempty `subtype`, or otherwise to `object_type`. Set `experiment_list` explicitly to target the experiments list instead of experiment details. Use the same scope when creating and listing columns

## Response `200`

Returns a list of custom column objects

- object
  - `objects` CustomColumn[], required
    - `id` string, uuid, required: Unique identifier for the custom columns
    - `object_type` 'organization' | 'project' | 'experiment' | 'dataset' | 'prompt' | 'prompt_session' | 'group' | 'role' | 'org_member' | 'project_log' | 'org_project' | 'org_audit_logs' | 'project_group' | 'project_group_projects' | 'ai_secret' | 'org_ai_secret' | 'org_account', required: The object type that the ACL applies to
    - `object_id` string, uuid, required: The id of the object the custom column is scoped for
    - `subtype` union, required: The object type that the ACL applies to
      - 'organization' | 'project' | 'experiment' | 'dataset' | 'prompt' | 'prompt_session' | 'group' | 'role' | 'org_member' | 'project_log' | 'org_project' | 'org_audit_logs' | 'project_group' | 'project_group_projects' | 'ai_secret' | 'org_ai_secret' | 'org_account': The object type that the ACL applies to
      - ''
    - `variant` 'project' | 'experiment' | 'dataset' | 'project_log' | 'experiment_list', required: The table variant that the custom column applies to
    - `name` string, required: The name of the custom column
    - `expr` string, required: The expression used to extract the value for the custom column
    - `created` string, date-time, nullable: Date of custom columns creation

## Other responses

- `400`: The request was unacceptable, often due to missing a required parameter
- `401`: No valid API key provided
- `403`: The API key doesn’t have permissions to perform the request
- `429`: Too many requests hit the API too quickly. We recommend an exponential backoff of your requests
- `500`: Something went wrong on Braintrust's end. (These are rare.)

## Changes

- **2026-11-04** `19184ec94018`: 1 info
  - endpoint added

[Operation history](https://skmtc.dev/braintrustdata/apis/braintrust-api/changes/v1/column/get.md)

---

[API](https://skmtc.dev/braintrustdata/apis/braintrust-api.md) - [All operations](https://skmtc.dev/braintrustdata/apis/braintrust-api/llms.txt) - [OpenAPI document](https://skmtc.dev/braintrustdata/apis/braintrust-api/revisions/19184ec94018?raw)