> ## Documentation Index
> Fetch the complete documentation index at: https://docs.useboom.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Upsert object

> Create or update a custom object by type and external id. The type must already exist; free-form attributes are fully replaced.



## OpenAPI

````yaml /api-reference/openapi.json post /api/v1/cdp/custom-objects
openapi: 3.1.0
info:
  title: Boom API
  version: 1.0.0
  description: >-
    Boom's public REST API — one uniform surface over every platform capability.
    CDP: upsert people and custom objects, define object and relationship types,
    link and unlink relationships, and record behavioral events — one record per
    request or up to 1000 per request via the `/batch` endpoints. Segments: read
    (list, read, membership) and full authoring — discover the filterable
    catalog, validate a filter, create and update segments, preview match
    counts, and trigger evaluation. Initiatives: create and configure outreach
    initiatives, link WhatsApp templates, drive the lifecycle (launch, cancel,
    archive), and read collected-data summaries. Participants: enroll people
    into an active initiative, track their status, read conversation
    transcripts, and stop outreach. Journeys: read-only access to always-on
    message flows and their metrics. WhatsApp templates: list your WhatsApp
    numbers and list, read, and create message templates. The same capabilities
    are exposed as MCP tools with identical schemas.
servers:
  - url: https://www.useboom.ai
    description: Production
  - url: https://dev.useboom.ai
    description: Development (sandbox — use a development organization API key)
security:
  - bearerAuth: []
paths:
  /api/v1/cdp/custom-objects:
    post:
      tags:
        - CDP Custom Objects
      summary: Upsert object
      description: >-
        Create or update a custom object by type and external id. The type must
        already exist; free-form attributes are fully replaced.
      operationId: cdp_custom_objects_upsert
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $schema: https://json-schema.org/draft/2020-12/schema
              type: object
              properties:
                type:
                  type: string
                  minLength: 1
                  maxLength: 255
                  description: >-
                    The custom object type name. Must already exist (create it
                    with the types endpoint) — unknown types are rejected.
                externalId:
                  type: string
                  minLength: 1
                  maxLength: 255
                  description: >-
                    Your stable identifier for this object within its type
                    (idempotency key).
                displayName:
                  description: Human-readable label for the object.
                  type: string
                  minLength: 1
                  maxLength: 255
                attributes:
                  description: Free-form custom traits (full-replace on upsert).
                  type: object
                  propertyNames:
                    type: string
                    maxLength: 255
                  additionalProperties: {}
              required:
                - type
                - externalId
      responses:
        '200':
          description: Success
          content:
            application/json:
              schema:
                $schema: https://json-schema.org/draft/2020-12/schema
                type: object
                properties:
                  type:
                    type: string
                  externalId:
                    type: string
                  created:
                    type: boolean
                required:
                  - type
                  - externalId
                  - created
                additionalProperties: false
        '400':
          description: Validation failed or the request cannot proceed.
          content:
            application/json:
              schema:
                type: object
                properties:
                  error:
                    type: object
                    properties:
                      code:
                        type: string
                        description: Stable machine-readable error code (snake_case).
                      message:
                        type: string
                    required:
                      - code
                      - message
                required:
                  - error
        '401':
          description: Missing, malformed, or revoked API key.
          content:
            application/json:
              schema:
                type: object
                properties:
                  error:
                    type: object
                    properties:
                      code:
                        type: string
                        description: Stable machine-readable error code (snake_case).
                      message:
                        type: string
                    required:
                      - code
                      - message
                required:
                  - error
        '404':
          description: The resource does not exist in this organization.
          content:
            application/json:
              schema:
                type: object
                properties:
                  error:
                    type: object
                    properties:
                      code:
                        type: string
                        description: Stable machine-readable error code (snake_case).
                      message:
                        type: string
                    required:
                      - code
                      - message
                required:
                  - error
        '409':
          description: >-
            Conflicts with the current state (duplicates, wrong lifecycle
            state).
          content:
            application/json:
              schema:
                type: object
                properties:
                  error:
                    type: object
                    properties:
                      code:
                        type: string
                        description: Stable machine-readable error code (snake_case).
                      message:
                        type: string
                    required:
                      - code
                      - message
                required:
                  - error
        '422':
          description: The request is well-formed but semantically invalid.
          content:
            application/json:
              schema:
                type: object
                properties:
                  error:
                    type: object
                    properties:
                      code:
                        type: string
                        description: Stable machine-readable error code (snake_case).
                      message:
                        type: string
                    required:
                      - code
                      - message
                required:
                  - error
        '429':
          description: Rate limit exceeded — retry after `Retry-After`.
          content:
            application/json:
              schema:
                type: object
                properties:
                  error:
                    type: object
                    properties:
                      code:
                        type: string
                        description: Stable machine-readable error code (snake_case).
                      message:
                        type: string
                    required:
                      - code
                      - message
                required:
                  - error
        '500':
          description: Internal server error.
          content:
            application/json:
              schema:
                type: object
                properties:
                  error:
                    type: object
                    properties:
                      code:
                        type: string
                        description: Stable machine-readable error code (snake_case).
                      message:
                        type: string
                    required:
                      - code
                      - message
                required:
                  - error
        '503':
          description: Transient error — retry with a narrower request.
          content:
            application/json:
              schema:
                type: object
                properties:
                  error:
                    type: object
                    properties:
                      code:
                        type: string
                        description: Stable machine-readable error code (snake_case).
                      message:
                        type: string
                    required:
                      - code
                      - message
                required:
                  - error
components:
  securitySchemes:
    bearerAuth:
      type: http
      scheme: bearer
      description: 'Organization API key, sent as `Authorization: Bearer boom_org_...`.'

````