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POST
Merge Project Data Definition
Closed Beta
Available to a limited set of invited customers. Contact your account team to join. The request and response contract may change before general availability (GA).

Permissions

The permissions required to access this endpoint. See Permissions Reference for what each role grants.

Required Permissions: merge_events_properties write_data_definitions

Granted By Role: Owner

Authorizations

Authorization
string
header
required

This endpoint uses Service Account authentication.

Headers

Mixpanel-Version
string
default:2026-08-13

Optional date-based API version pin.

If omitted, the request is served by the latest API version, and the caller accepts that a future release may introduce a breaking change to the response contract. If set to a supported version date, that version's contract is honored and will not receive a breaking change.

Idempotency-Key
string

Optional, client-provided key guaranteeing the operation is idempotent on success: if a request is replayed, the response includes Idempotent-Replayed: true.

Reusing a key with a different request body, or while a request with the same key is still in flight, returns a 409.

Use a unique, random value for each request (a UUID v4 works well).

Maximum string length: 255

Path Parameters

project_id
string
required

The unique identifier for the project.

Body

application/json

Fold sources into canonical, all of one type. Exactly one merge per request.

type
enum<string>
required

The kind of definition to merge.

Available options:
event,
event_property
canonical
string
required

Name of the definition the sources merge into.

Required string length: 1 - 255
sources
string[]
required

Names of the definitions merged into the canonical.

Required array length: 1 - 100 elements
Required string length: 1 - 255

Response

OK

canonical
DataDefinitionRef · object
required

The definition the sources merged into.

sources
DataDefinitionRef · object[]
required

The definitions merged into the canonical.