> ## Documentation Index > Fetch the complete documentation index at: https://docs.business.blaaiz.com/llms.txt > Use this file to discover all available pages before exploring further. # Register a KYB document > Use after PUTting a file to the presigned URL. The server verifies that the upload exists, checks size and MIME, and stores the document with status `PENDING`. Max file size 25 MB. Allowed MIME: `application/pdf`, `image/jpeg`, `image/png`. Files that fail these checks return 422. **Formation documents are required for verification.** When you call `POST /api/external/customer/{customer}/submit`, at least one document of a formation type must be present. Formation types are: `CERTIFICATE_OF_INCORPORATION`, `ARTICLES_OF_INCORPORATION`, `BENEFICIAL_OWNERSHIP_CERTIFICATE`, `INCORPORATION_DOCUMENTS`, `CAC_STATUS_REPORT`. Other types may be required by your compliance reviewer depending on the business profile. All uploaded documents must be **clear, legible, and authentic**. Blurry, cropped, obscured, or otherwise unclear images will be rejected. Fraudulent or falsified documents will not be tolerated — repeated attempts to submit false or invalid documents will result in the customer being **permanently blacklisted** from the platform. There are no exceptions or compromises. The customer must be of type `business`. Required scope: `customer:write`. ## OpenAPI ````yaml /api-reference/customer/register-document-openapi.json post /api/external/customer/{customer}/document openapi: 3.1.0 info: title: Blaaiz Platform API - Register KYB Document version: 1.0.0 description: >- Step two of the two-step KYB document upload flow. Attach a previously-uploaded file to the customer's KYB document collection. The customer must be of type `business`. The customer must not be locked for review (must be in PENDING or REJECTED state). servers: - url: https://api-prod.blaaiz.com - url: https://api-dev.blaaiz.com security: [] tags: - name: Customer paths: /api/external/customer/{customer}/document: post: tags: - Customer summary: Register a KYB document description: >- Use after PUTting a file to the presigned URL. The server verifies that the upload exists, checks size and MIME, and stores the document with status `PENDING`. Max file size 25 MB. Allowed MIME: `application/pdf`, `image/jpeg`, `image/png`. Files that fail these checks return 422. **Formation documents are required for verification.** When you call `POST /api/external/customer/{customer}/submit`, at least one document of a formation type must be present. Formation types are: `CERTIFICATE_OF_INCORPORATION`, `ARTICLES_OF_INCORPORATION`, `BENEFICIAL_OWNERSHIP_CERTIFICATE`, `INCORPORATION_DOCUMENTS`, `CAC_STATUS_REPORT`. Other types may be required by your compliance reviewer depending on the business profile. All uploaded documents must be **clear, legible, and authentic**. Blurry, cropped, obscured, or otherwise unclear images will be rejected. Fraudulent or falsified documents will not be tolerated — repeated attempts to submit false or invalid documents will result in the customer being **permanently blacklisted** from the platform. There are no exceptions or compromises. The customer must be of type `business`. Required scope: `customer:write`. parameters: - name: customer in: path required: true schema: type: string format: uuid requestBody: required: true content: application/json: schema: type: object required: - type - name - file_id properties: type: type: string description: >- Document type. Determines whether the document satisfies the formation-document requirement at submit time. enum: - CERTIFICATE_OF_INCORPORATION - ARTICLES_OF_INCORPORATION - BENEFICIAL_OWNERSHIP_CERTIFICATE - INCORPORATION_DOCUMENTS - CAC_STATUS_REPORT - ACCOUNT_AGREEMENT - PROOF_OF_ADDRESS - BANK_STATEMENT - LICENSE - SHARE_REGISTRATION - COMPANY_OWNERSHIP_STRUCTURE - DIRECTORS_REGISTER - OTHER example: CERTIFICATE_OF_INCORPORATION name: type: string maxLength: 255 example: Acme Inc — Certificate of Incorporation.pdf file_id: type: string format: uuid description: >- The `file_id` returned by POST /api/external/customer/{customer}/document/presigned-url. description: type: string maxLength: 2000 nullable: true example: Filed 2019-03-12, Companies House responses: '201': description: Document registered. content: application/json: example: message: Document created successfully data: id: 019a6e10-1fb3-7b2f-8f8b-ad1e92c4017a business_customer_id: 019a6da3-4a9a-7033-81b9-12489eff13ee type: CERTIFICATE_OF_INCORPORATION name: Acme Inc — Certificate of Incorporation.pdf extension: pdf description: Filed 2019-03-12, Companies House status: PENDING admin_comments: null url: https://s3.amazonaws.com/...?X-Amz-Signature=... created_at: '2026-04-20T10:14:31.000000Z' updated_at: '2026-04-20T10:14:31.000000Z' '400': description: >- Customer is verified or under review and cannot accept new documents. content: application/json: example: message: >- Cannot modify documents while customer verification is in progress. '401': description: Unauthorized. '404': description: Customer not found. '422': description: Validation error or uploaded file failed size/MIME checks. content: application/json: example: message: Document file exceeds the 25 MB maximum. security: - oauth2ClientCredentials: - customer:write components: securitySchemes: oauth2ClientCredentials: type: oauth2 flows: clientCredentials: tokenUrl: /oauth/token scopes: customer:write: Create and update customers and KYC data. ````