> ## Documentation Index > Fetch the complete documentation index at: https://docs.filexpress.app/llms.txt > Use this file to discover all available pages before exploring further. # Create customer > Creates a customer. Legacy response format `{ success, data, message }`. **Required permission:** `customers` ## OpenAPI ````yaml /api-reference/openapi.en.json post /customers openapi: 3.0.3 info: title: FileXpress External API version: 1.0.0 description: >- API for integrating third-party systems with FileXpress: billing, HR, accounting, inventory, projects, accounts receivable and payable, treasury, pricing and promotions, and cash. Current base URL: /api/external/v1. The legacy unversioned path (/api/external) will be removed on January 1, 2027; migrate to /api/external/v1 (same endpoints, only the base URL changes). The v2 API (/api/external/v2) exposes currencies and exchange rates, sales and purchases in foreign currency, taxes by id, payrolls with branch, and errors with a stable `code`; its operations carry the /v2 prefix in the path. We suggest migrating to the available v2 routes before March 30, 2027. servers: - url: https://api.filexpress.app/api/external/v1 description: Production security: - ApiKey: [] tags: - name: General - name: Billing · Sales - name: Billing · Purchases - name: Billing · Customers - name: Billing · Suppliers - name: Billing · Products - name: Catalogs - name: HR · Employees - name: HR · Attendance - name: HR · Labor rules - name: HR · Schedules - name: HR · Holidays - name: HR · Attendance results - name: HR · Leave requests - name: HR · Payrolls - name: Accounting - name: Inventory - name: Projects - name: Accounts receivable - name: Accounts payable - name: Treasury - name: Pricing and promotions - name: Cash - name: Points of sale - name: API v2 · General - name: API v2 · Currencies and rates - name: API v2 · Countries - name: API v2 · Sales - name: API v2 · Purchases - name: API v2 · Payrolls paths: /customers: post: tags: - Billing · Customers summary: Create customer description: |- Creates a customer. Legacy response format `{ success, data, message }`. **Required permission:** `customers` requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/CustomerRequest' example: customer_name: Juan Pérez legal_name: Juan Antonio Pérez García register_number: 12345-6 tax_number: 0614-000101-000-0 document_type: '13' document_number: 00000000-0 address: 'Col. San Benito, Av. La Revolución #123' country_id: 9d1c5a3e-4b7f-4e2a-9c1d-2f6b8a0e7c11 state_id: 9d1c5a3e-4b7f-4e2a-9c1d-2f6b8a0e7c11 city_id: 9d1c5a3e-4b7f-4e2a-9c1d-2f6b8a0e7c11 activity_id: 9d1c5a3e-4b7f-4e2a-9c1d-2f6b8a0e7c11 phone: 7777-1234 email: juan@example.com business_type: natural branch_id: 9d1c5a3e-4b7f-4e2a-9c1d-2f6b8a0e7c11 responses: '200': description: Customer created content: application/json: example: success: true data: id: 9d1c5a3e-4b7f-4e2a-9c1d-2f6b8a0e7c11 customer_name: Juan Pérez legal_name: Juan Antonio Pérez García register_number: 12345-6 tax_number: 0614-000101-000-0 document_type: '13' document_number: 00000000-0 address: 'Col. San Benito, Av. La Revolución #123' country_id: 9d1c5a3e-4b7f-4e2a-9c1d-2f6b8a0e7c11 state_id: 9d1c5a3e-4b7f-4e2a-9c1d-2f6b8a0e7c11 city_id: 9d1c5a3e-4b7f-4e2a-9c1d-2f6b8a0e7c11 activity_id: 9d1c5a3e-4b7f-4e2a-9c1d-2f6b8a0e7c11 phone: 7777-1234 email: juan@example.com business_type: natural message: Data retrieved successfully. '401': $ref: '#/components/responses/E401' '403': $ref: '#/components/responses/E403' '404': $ref: '#/components/responses/ELegacyValidation' '429': $ref: '#/components/responses/E429' components: schemas: CustomerRequest: type: object properties: customer_name: type: string legal_name: type: string register_number: type: string description: NRC. tax_number: type: string description: NIT. document_type: type: string description: Document type code (13 = DUI, 36 = NIT...). document_number: type: string address: type: string country_id: type: string format: uuid state_id: type: string format: uuid description: Required for El Salvador; optional if country_id is another country. city_id: type: string format: uuid description: Required for El Salvador; optional if country_id is another country. state_name: type: string maxLength: 120 description: >- Department or state as free text. Required if country_id is not El Salvador. city_name: type: string maxLength: 120 description: >- City or municipality as free text. Required if country_id is not El Salvador. activity_id: type: string format: uuid phone: type: string email: type: string business_type: type: string description: Customer type. enum: - non-business - natural - legal branch_id: type: string format: uuid required: - customer_name - address - country_id - phone - email - business_type - branch_id responses: E401: description: Missing or invalid API Key content: application/json: example: status: false message: Invalid API Key. E403: description: Integration without the required permission or deactivated content: application/json: example: status: false message: This integration does not have the 'hr.employees' permission. required_scope: hr.employees ELegacyValidation: description: 'Validation error (legacy format: returns 404)' content: application/json: example: success: false message: Validation Error. data: email: - The email field is required. E429: description: Rate limit exceeded content: application/json: example: status: false message: Rate limit exceeded. Please try again later. rate_limit: 100 securitySchemes: ApiKey: type: apiKey in: header name: X-API-Key description: Integration API Key (Integrations → New Integration). ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.