> ## 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 person > Create or update a person by external id. Attributes are merged into the stored ones by default (omitted keys kept, null removes a key); pass mode:'replace' to swap the whole set. ## OpenAPI ````yaml /api-reference/openapi.json post /api/v1/cdp/people 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/people: post: tags: - CDP People summary: Upsert person description: >- Create or update a person by external id. Attributes are merged into the stored ones by default (omitted keys kept, null removes a key); pass mode:'replace' to swap the whole set. operationId: cdp_people_upsert requestBody: required: true content: application/json: schema: $schema: https://json-schema.org/draft/2020-12/schema type: object properties: externalId: type: string minLength: 1 maxLength: 255 description: Your stable identifier for this person (idempotency key). firstName: description: Given name. anyOf: - type: string maxLength: 255 - type: 'null' lastName: description: Family name. anyOf: - type: string maxLength: 255 - type: 'null' email: description: Email address. anyOf: - type: string maxLength: 255 - type: 'null' phoneNumber: description: Phone number in E.164 format (e.g. +5215555555555). anyOf: - type: string maxLength: 255 - type: 'null' attributes: description: >- Free-form custom traits. Merged into the stored ones by default: keys you omit are kept, and a key sent as null is removed. Pass mode:'replace' to swap the whole set. type: object propertyNames: type: string maxLength: 255 additionalProperties: {} mode: default: merge description: >- How `attributes` and the profile fields are applied. 'merge' (default) overlays the attributes you send onto the stored ones: omitted keys are kept, a key sent as null is removed, and an omitted or null profile field (firstName, lastName, email, phoneNumber) keeps its stored value. 'replace' swaps the whole attribute set (any key you leave out is DELETED) and writes every profile field as sent, so an omitted one is cleared. type: string enum: - merge - replace required: - externalId responses: '200': description: Success content: application/json: schema: $schema: https://json-schema.org/draft/2020-12/schema type: object properties: externalId: type: string created: type: boolean required: - 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_...`.' ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.