> ## Documentation Index > Fetch the complete documentation index at: https://docs.embedreach.com/llms.txt > Use this file to discover all available pages before exploring further. # Patch Customer Resource > Updates a customer resource by its external ID. This is an incremental update, only provided fields will be updated. ## OpenAPI ````yaml PATCH /api/resources/customers/{externalId} openapi: 3.0.0 info: title: Reach API version: 1.0.0 description: API documentation for Reach platform servers: - url: https://api.embedreach.com description: Production server security: [] paths: /api/resources/customers/{externalId}: patch: tags: - Default Partner Resources summary: Patch Customer Resource description: >- Updates a customer resource by its external ID. This is an incremental update, only provided fields will be updated. parameters: - name: reach-tenant-id in: header required: false schema: type: string description: >- If using a platform scoped JWT, you can pass in a header to impersonate a specific tenant to impersonate the request as. - schema: type: string description: The external ID of the customer resource to update required: true description: The external ID of the customer resource to update name: externalId in: path - schema: type: boolean nullable: true default: false description: >- Whether to allow extra fields that are not defined in the schema. If true, extra fields will be accepted but not saved. If false, requests with extra fields will be rejected. required: false description: >- Whether to allow extra fields that are not defined in the schema. If true, extra fields will be accepted but not saved. If false, requests with extra fields will be rejected. name: ignoreUnknownFields in: query requestBody: content: application/json: schema: type: object properties: data: type: object properties: customerId: type: string email: type: string phone: type: string firstName: type: string lastName: type: string emailOptOut: type: boolean description: >- Email subscription opt-out status. Defaults to false (opted in) smsOptOut: type: boolean description: >- SMS subscription opt-out status. Defaults to true (opted out) customerDetailUrl: type: string description: URL to click-out to the customer detail page createdAt: type: string format: date-time description: Partial customer resource data for incremental update required: - data responses: '200': description: Status 200 response content: application/json: schema: type: object properties: success: type: boolean message: type: string data: type: object properties: result: type: object properties: id: type: string format: uuid description: Unique identifier for the resource schema_definition_id: type: string format: uuid description: >- [Deprecated] Please use schemaDefinitionId instead. ID of the schema definition for this resource schemaDefinitionId: type: string format: uuid description: ID of the schema definition for this resource platform_id: type: string format: uuid description: >- [Deprecated] Please use platformId instead. ID of the platform this resource belongs to platformId: type: string format: uuid description: ID of the platform this resource belongs to business_id: type: string format: uuid description: >- [Deprecated] Please use businessId instead. ID of the business this resource belongs to businessId: type: string format: uuid description: ID of the business this resource belongs to resource_external_id: type: string description: External ID of the resource resourceExternalId: type: string description: >- [Deprecated] Please use resourceExternalId instead. External ID of the resource created_at: type: string description: '[Deprecated] Please use createdAt instead' createdAt: type: string description: Creation timestamp updated_at: type: string description: '[Deprecated] Please use updatedAt instead' updatedAt: type: string description: Last update timestamp data: type: object properties: customerId: type: string email: type: string phone: type: string firstName: type: string lastName: type: string emailOptOut: type: boolean description: >- Email subscription opt-out status. Defaults to false (opted in) smsOptOut: type: boolean description: >- SMS subscription opt-out status. Defaults to true (opted out) customerDetailUrl: type: string description: URL to click-out to the customer detail page createdAt: type: string format: date-time required: - customerId - firstName - lastName - createdAt required: - id - schema_definition_id - schemaDefinitionId - platform_id - platformId - business_id - businessId - resource_external_id - resourceExternalId - created_at - createdAt - updated_at - updatedAt - data included: type: array items: type: object properties: id: type: string format: uuid description: Unique identifier for the resource schema_definition_id: type: string format: uuid description: >- [Deprecated] Please use schemaDefinitionId instead. ID of the schema definition for this resource schemaDefinitionId: type: string format: uuid description: ID of the schema definition for this resource platform_id: type: string format: uuid description: >- [Deprecated] Please use platformId instead. ID of the platform this resource belongs to platformId: type: string format: uuid description: ID of the platform this resource belongs to business_id: type: string format: uuid description: >- [Deprecated] Please use businessId instead. ID of the business this resource belongs to businessId: type: string format: uuid description: ID of the business this resource belongs to resource_external_id: type: string description: External ID of the resource resourceExternalId: type: string description: >- [Deprecated] Please use resourceExternalId instead. External ID of the resource created_at: type: string description: '[Deprecated] Please use createdAt instead' createdAt: type: string description: Creation timestamp updated_at: type: string description: '[Deprecated] Please use updatedAt instead' updatedAt: type: string description: Last update timestamp data: type: object properties: customerId: type: string email: type: string phone: type: string firstName: type: string lastName: type: string emailOptOut: type: boolean description: >- Email subscription opt-out status. Defaults to false (opted in) smsOptOut: type: boolean description: >- SMS subscription opt-out status. Defaults to true (opted out) customerDetailUrl: type: string description: URL to click-out to the customer detail page createdAt: type: string format: date-time required: - customerId - firstName - lastName - createdAt required: - id - schema_definition_id - schemaDefinitionId - platform_id - platformId - business_id - businessId - resource_external_id - resourceExternalId - created_at - createdAt - updated_at - updatedAt - data description: >- Included resources when specified in the include parameter required: - result required: - success '400': description: Bad Request - Validation or request error content: application/json: schema: type: object properties: success: type: boolean enum: - false default: false message: type: string description: Error message describing what went wrong errors: type: array items: type: string description: Optional array of specific validation errors required: - message '404': description: Status 404 response content: application/json: schema: type: object properties: success: type: boolean message: type: string data: type: object properties: error: type: string required: - error required: - success ````