---
title: "Update an experiment by ID"
method: PATCH
path: "/v1/experiments/{experiment_id}"
tags: ["experiments"]
---

# Update an experiment by ID

`PATCH /v1/experiments/{experiment_id}`

Partially update an experiment's name, description, and/or metadata. Only the fields included in the request body are changed; omitted fields are left as-is. Patching an ephemeral experiment refreshes its last-update timestamp, which extends the window before it is swept away.

## Path parameters

- `experiment_id` string, required

## Request body

- UpdateExperimentRequestBody — Fields to update on an experiment. Omit a field to leave it unchanged.
  - `name` string, nullable — New name for the experiment (null is rejected; name is required)
  - `description` string, nullable — New description for the experiment (null clears the description)
  - `metadata` object, nullable — New metadata object for the experiment (replaces the existing metadata as a whole; null is rejected)

## Response `200`

Experiment updated successfully

- UpdateExperimentResponseBody
  - `data` Experiment, required
    - `id` string, required — The ID of the experiment
    - `dataset_id` string, required — The ID of the dataset associated with the experiment
    - `dataset_version_id` string, required — The ID of the dataset version associated with the experiment
    - `name` string, required — The name of the experiment
    - `description` string, nullable, required — The description of the experiment
    - `repetitions` integer, required — Number of times the experiment is repeated
    - `metadata` object, required — Metadata of the experiment
    - `project_name` string, nullable, required — The name of the project associated with the experiment
    - `created_at` string, date-time, required — The creation timestamp of the experiment
    - `updated_at` string, date-time, required — The last update timestamp of the experiment
    - `example_count` integer, required — Number of examples in the experiment
    - `successful_run_count` integer, required — Number of successful runs in the experiment
    - `failed_run_count` integer, required — Number of failed runs in the experiment
    - `missing_run_count` integer, required — Number of missing (not yet executed) runs in the experiment

## Other responses

- `403` — Forbidden
- `404` — Experiment not found
- `422` — Invalid experiment ID or request body

---

[API](https://skmtc.net/arize-ai/apis/arize-phoenix-rest-api.md) · [All operations](https://skmtc.net/arize-ai/apis/arize-phoenix-rest-api/llms.txt) · [OpenAPI document](https://skmtc-service-staging.skmtc.workers.dev/v1/apis/arize-ai/arize-phoenix-rest-api/versions/5339b2afd3a2/schema)