Conclude an experiment

Ends an experiment for good: the winning arm, or the control without one, becomes the paywall shown at each of its locations.

Guide: Feature flags and A/B tests

Errors

Status	`type`	`code`	When
400	`invalid_request`	`experiment_variant_not_found`	When the winner is not one of its arms.
409	`conflict`	`experiment_not_started`	For a draft.
409	`conflict`	`experiment_concluded`	When already concluded.

It can also fail with the errors every operation shares, such as unauthenticated; see Errors.

More in Experiments

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Path parameters

projectId*string

The project's id, proj_.... A secret key works only in the project it belongs to.

experimentId*string

The experiment's id, exp_....

Request body

application/json

TypeScript definitions

Use the request body type in TypeScript.

winningVariantId?|

The arm to promote, exp_var_...; omitted, the control arm is promoted.

Examples

curl -X POST "https://api.voidhash.com/api/v1/projects/proj_tz4a98xxat96iws9zmbrgj3a/experiments/exp_c6v8b3n5q0w2e7h7d2k9m4x1/conclude" \  -H "Authorization: Bearer vh_sk_..." \  -H "Content-Type: application/json" \  -d '{    "winningVariantId": "exp_var_n5q0w2e7h7d2k9m4x1c6v8b3"  }'

{  "id": "exp_c6v8b3n5q0w2e7h7d2k9m4x1",  "projectId": "proj_tz4a98xxat96iws9zmbrgj3a",  "name": "Onboarding paywall pricing",  "description": "The monthly-first paywall against the annual-first one after onboarding.",  "hypothesis": "Leading with the annual plan brings more new subscriptions.",  "status": "concluded",  "primaryMetricEventName": "$subscription.created",  "secondaryMetricEventNames": [],  "paywallLocationIds": [    "pw_loc_m4x1c6v8b3n5q0w2e7h7d2k9"  ],  "winningVariantId": "exp_var_n5q0w2e7h7d2k9m4x1c6v8b3",  "featureFlagId": "ff_k9m4x1c6v8b3n5q0w2e7h7d2",  "isArchived": false,  "startedAt": "2026-03-02T09:00:00.000Z",  "endedAt": "2026-04-01T09:00:00.000Z",  "createdAt": "2026-02-27T15:20:00.000Z",  "updatedAt": "2026-04-01T09:00:00.000Z"}

{  "error": {    "type": "invalid_request",    "code": "experiment_variant_not_found",    "message": "This experiment has no arm exp_var_q8w2e6r4t0y3u9b7m3x9c5v1.",    "param": "winningVariantId"  }}

{  "error": {    "type": "unauthenticated",    "code": "invalid_api_key",    "message": "This secret key is not valid."  }}

{  "error": {    "type": "permission_denied",    "code": "permission_denied",    "message": "Insufficient permissions."  }}

{  "error": {    "type": "not_found",    "code": "project_not_found",    "message": "There is no project proj_tz4a98xxat96iws9zmbrgj3a, or this credential cannot use it.",    "param": "projectId"  }}

{  "error": {    "type": "conflict",    "code": "experiment_not_started",    "message": "Experiment exp_c6v8b3n5q0w2e7h7d2k9m4x1 has not started; there is nothing to conclude."  }}

{  "error": {    "type": "internal",    "code": "internal_error",    "message": "Something went wrong on our side. Try again, and contact support with the Request-Id header if it keeps failing."  }}

Conclude an experiment

Errors

More in Experiments

Conclude an experiment

Errors

More in Experiments

Authorization

Path parameters

Request body

Examples

Response body

`application/json`

`application/json`

`application/json`

`application/json`

`application/json`

`application/json`

`application/json`

Conclude an experiment

Conclude an experiment

experiment_not_started

experiment_concluded

200application/json

400application/json

401application/json

403application/json

404application/json

409application/json

500application/json

`application/json`

`application/json`

`application/json`

`application/json`

`application/json`

`application/json`

`application/json`