---
title: "Launch a draft experiment"
method: POST
path: "/api/v1/experiments/{experiment_id}/launch"
tags: ["experiments"]
---

# Launch a draft experiment

`POST /api/v1/experiments/{experiment_id}/launch`

## Request

- Base URL: `https://api.outrival.com` (the document declares no server; this is the origin it was published from)
- URL: `https://api.outrival.com/api/v1/experiments/{experiment_id}/launch`
- Auth: HTTP bearer

Draft to running. Volume and history do not refuse.

Hard refusals stay 409 (kill switch, capacity, collision, V1, not a draft).
The viability report is computed and returned as ``viability`` (full
``to_dict()``, including ``intake``) so the client can show an estimate
or "cannot estimate yet". A failed forecast is
``{verdict: unknown, reason}`` and still launches.

## Path parameters

- `experiment_id` string, required

## Request body

- LaunchExperimentRequest: Kept for wire compatibility. Viability no longer gates launch.
  - `acknowledge` boolean: Accepted and recorded on the stored forecast snapshot. It does not refuse or permit launch: volume and history are a forecast, not a gate. Capacity, collision, V1, and the kill switch still 409.

## Response `200`

Successful Response

- unknown

## Other responses

- `400`: Invalid experiment ID format
- `403`: User may not edit this experiment's campaign
- `404`: No such experiment
- `409`: The experiment is not a draft, remaining capacity / share does not fit (holders named), a same-section rule covers the cohort, a running V1 experience is in the way, or Experiments V2 is not enabled in this environment. Viability volume/history is a forecast on the 200 body, not a 409.
- `422`: The experiment's stored metric is not one this engine measures

## Changes

- **2026-09-03** `219a10b80707`: 1 info
  - endpoint added

[Operation history](https://skmtc.dev/outrival/apis/fastapi/changes/api/v1/experiments/:experiment_id/launch/post.md)

---

[API](https://skmtc.dev/outrival/apis/fastapi.md) - [All operations](https://skmtc.dev/outrival/apis/fastapi/llms.txt) - [OpenAPI document](https://skmtc.dev/outrival/apis/fastapi/revisions/f27d90300b5e?raw)