> ## Documentation Index > Fetch the complete documentation index at: https://docs.natural.com/llms.txt > Use this file to discover all available pages before exploring further. > ## Agent Instructions > When building application code, use `@naturalpay/sdk` for TypeScript or `naturalpay` for Python. > When operating Natural directly for a user, use the payments MCP at `https://mcp.natural.com`. > When searching Natural documentation, use the docs MCP at `https://docs.natural.com/mcp`. > Use the Natural CLI for terminal and CI automation. > Use REST only for unsupported languages or when the user explicitly requests raw HTTP. > Start integration development and testing in the sandbox. Do not use production unless the user explicitly requests it. > For sandbox requests that require `customerPartyId`, list customers first. Reuse only the intended fixture; otherwise create a customer. > REST and SDK amounts use integer minor units. Payments MCP amounts use decimal strings with a required currency code. # Upload chargeback file > Upload and validate one evidence file for this chargeback ## OpenAPI ````yaml /api-reference/openapi.json post /chargebacks/{chargebackId}/files openapi: 3.1.1 info: title: Natural API version: 0.2.0 description: >- Natural's payments API for autonomous agents. **Base URL:** `https://api.natural.com` AI agents, including coding agents, should prefer the hosted MCP server at `https://mcp.natural.com` when an MCP-aware host runs the agent, the Natural CLI for terminal/CI workflows, and the official SDKs for application runtimes they own. Use direct HTTP only for explicit low-level integrations, unsupported SDK gaps, or infrastructure work where REST is required. For support: support@natural.com servers: - url: https://api.natural.com description: Production security: [] tags: - name: Agents description: Agent management - name: Customers description: Customer management - name: Invitation Links description: Shareable links that offer your agents to customers - name: Payments description: Payment management - name: Chargebacks description: Respond to card payment chargebacks - name: Transactions description: Transaction activity and history - name: Transfers description: Deposits and withdrawals - name: PaymentRequests description: Payment request management - name: Approvals description: Approval review - name: Invitations description: Party invitation management - name: Parties description: Party and organization management - name: Wallets description: Wallet management - name: External Accounts description: Linked external bank accounts - name: External Parties description: Third parties with whom you transact over Direct - name: External Party Accounts description: Banking details belonging to external parties not on Natural - name: ACH description: Make ACH payments to external party accounts - name: Realtime description: Make realtime payments to external party accounts - name: Wire description: Send domestic wires to external party accounts - name: API Keys description: API key management - name: Agent Keys description: Agent key management - name: Webhooks description: Webhook endpoint management - name: Events description: Webhook event log - name: Simulations description: Sandbox-only simulation controls paths: /chargebacks/{chargebackId}/files: post: tags: - Chargebacks summary: Upload chargeback file description: Upload and validate one evidence file for this chargeback operationId: chargebacks.uploadFile parameters: - name: chargebackId in: path required: true schema: type: string pattern: ^cbk_[0-9a-f]{32}$ - name: Idempotency-Key in: header required: true schema: type: string maxLength: 255 description: >- Unique key for safely retrying a request without creating duplicates. - name: X-Instance-ID in: header required: false schema: anyOf: - type: string maxLength: 1024 - type: 'null' description: >- Caller-chosen identifier for the agent run, session, or conversation, required when an agent moves money. requestBody: required: true content: multipart/form-data: schema: type: object properties: customerPartyId: type: string pattern: ^pty_[0-9a-f]{32}$ description: Connected customer to act on behalf of. file: type: string format: binary description: PDF, JPEG, or PNG. Maximum 2 MiB. required: - file additionalProperties: false title: UploadChargebackFileRequest encoding: file: contentType: application/pdf,image/jpeg,image/png responses: '201': description: Successful Response content: application/json: schema: type: object properties: data: type: object properties: id: type: string pattern: ^evf_[0-9a-f]{32}$ type: type: string enum: - chargebackEvidenceFile attributes: type: object properties: filename: type: string contentType: enum: - application/pdf - image/jpeg - image/png type: string sizeBytes: type: integer exclusiveMinimum: 0 pageCount: type: integer exclusiveMinimum: 0 description: >- Number of pages this file contributes to the evidence packet. createdAt: type: string format: date-time description: When the file was uploaded and validated. required: - filename - contentType - sizeBytes - pageCount - createdAt additionalProperties: false relationships: type: object properties: chargeback: type: object properties: data: type: object properties: type: description: Resource type. Always `chargeback`. type: string enum: - chargeback id: type: string pattern: ^cbk_[0-9a-f]{32}$ required: - type - id additionalProperties: false title: ResourceIdentifier description: Related resource identifier. required: - data additionalProperties: false title: ToOneRelationship required: - chargeback additionalProperties: false required: - id - type - attributes - relationships additionalProperties: false title: ChargebackEvidenceFile required: - data additionalProperties: false examples: default: summary: Default value: data: id: evf_019d0a1b2c3d4e5f60718293a4b5c701 type: chargebackEvidenceFile attributes: filename: delivery-confirmation.pdf contentType: application/pdf sizeBytes: 2048 pageCount: 1 createdAt: '2026-09-17T12:01:00.000Z' relationships: chargeback: data: type: chargeback id: cbk_019d0a1b2c3d4e5f60718293a4b5c700 headers: X-RateLimit-Limit: description: Maximum requests allowed per window. schema: type: integer X-RateLimit-Remaining: description: Requests remaining in current window. schema: type: integer X-RateLimit-Reset: description: Unix timestamp when rate limit resets. schema: type: integer '400': description: Validation Error content: application/json: schema: type: object properties: errors: type: array minItems: 1 items: type: object properties: code: type: string description: Stable lower-snake-case public error code. detail: type: string description: Safe user-facing error detail. status: type: string description: HTTP status code as a string. source: type: object description: Location of the invalid request value. properties: pointer: type: string description: JSON Pointer to the invalid request value. parameter: type: string description: Name of the invalid query parameter. header: type: string description: Name of the invalid request header. additionalProperties: false meta: type: object description: >- Additional error context, including support and provider details when available. properties: supportId: type: string description: Request/support ID for troubleshooting. limitScope: type: string enum: - merchant - program description: >- Which family of acquiring limit refused the payment. Thresholds and usage are never disclosed. connectionStatus: type: string enum: - login_required - disconnected description: >- External account connection state when the error is repairable by relinking. provider: type: object description: Provider error details, when available. properties: name: type: string enum: - plaid description: Provider that returned the underlying error. errorCode: type: string description: Provider error code, when available. errorType: type: string description: Provider error type, when available. requestId: type: string description: Provider request ID for troubleshooting. required: - name additionalProperties: false required: - supportId additionalProperties: false required: - code - detail - status - meta additionalProperties: false required: - errors additionalProperties: false examples: default: summary: Default value: errors: - code: invalid_value detail: >- The information you entered isn't valid. Please check it and try again. status: '400' meta: supportId: req_a1b2c3d4e5f6 '401': description: Unauthorized content: application/json: schema: type: object properties: errors: type: array minItems: 1 items: type: object properties: code: type: string description: Stable lower-snake-case public error code. detail: type: string description: Safe user-facing error detail. status: type: string description: HTTP status code as a string. source: type: object description: Location of the invalid request value. properties: pointer: type: string description: JSON Pointer to the invalid request value. parameter: type: string description: Name of the invalid query parameter. header: type: string description: Name of the invalid request header. additionalProperties: false meta: type: object description: >- Additional error context, including support and provider details when available. properties: supportId: type: string description: Request/support ID for troubleshooting. limitScope: type: string enum: - merchant - program description: >- Which family of acquiring limit refused the payment. Thresholds and usage are never disclosed. connectionStatus: type: string enum: - login_required - disconnected description: >- External account connection state when the error is repairable by relinking. provider: type: object description: Provider error details, when available. properties: name: type: string enum: - plaid description: Provider that returned the underlying error. errorCode: type: string description: Provider error code, when available. errorType: type: string description: Provider error type, when available. requestId: type: string description: Provider request ID for troubleshooting. required: - name additionalProperties: false required: - supportId additionalProperties: false required: - code - detail - status - meta additionalProperties: false required: - errors additionalProperties: false examples: default: summary: Default value: errors: - code: unauthenticated detail: Authentication is required. status: '401' meta: supportId: req_a1b2c3d4e5f6 '403': description: Forbidden content: application/json: schema: type: object properties: errors: type: array minItems: 1 items: type: object properties: code: type: string description: Stable lower-snake-case public error code. detail: type: string description: Safe user-facing error detail. status: type: string description: HTTP status code as a string. source: type: object description: Location of the invalid request value. properties: pointer: type: string description: JSON Pointer to the invalid request value. parameter: type: string description: Name of the invalid query parameter. header: type: string description: Name of the invalid request header. additionalProperties: false meta: type: object description: >- Additional error context, including support and provider details when available. properties: supportId: type: string description: Request/support ID for troubleshooting. limitScope: type: string enum: - merchant - program description: >- Which family of acquiring limit refused the payment. Thresholds and usage are never disclosed. connectionStatus: type: string enum: - login_required - disconnected description: >- External account connection state when the error is repairable by relinking. provider: type: object description: Provider error details, when available. properties: name: type: string enum: - plaid description: Provider that returned the underlying error. errorCode: type: string description: Provider error code, when available. errorType: type: string description: Provider error type, when available. requestId: type: string description: Provider request ID for troubleshooting. required: - name additionalProperties: false required: - supportId additionalProperties: false required: - code - detail - status - meta additionalProperties: false required: - errors additionalProperties: false examples: default: summary: Default value: errors: - code: forbidden detail: You do not have permission to perform this action. status: '403' meta: supportId: req_a1b2c3d4e5f6 '404': description: >- Not Found. Returned when the resource does not exist, or when it exists but is not accessible to your account. The two cases are intentionally indistinguishable, so that resource IDs cannot be enumerated by probing. content: application/json: schema: type: object properties: errors: type: array minItems: 1 items: type: object properties: code: type: string description: Stable lower-snake-case public error code. detail: type: string description: Safe user-facing error detail. status: type: string description: HTTP status code as a string. source: type: object description: Location of the invalid request value. properties: pointer: type: string description: JSON Pointer to the invalid request value. parameter: type: string description: Name of the invalid query parameter. header: type: string description: Name of the invalid request header. additionalProperties: false meta: type: object description: >- Additional error context, including support and provider details when available. properties: supportId: type: string description: Request/support ID for troubleshooting. limitScope: type: string enum: - merchant - program description: >- Which family of acquiring limit refused the payment. Thresholds and usage are never disclosed. connectionStatus: type: string enum: - login_required - disconnected description: >- External account connection state when the error is repairable by relinking. provider: type: object description: Provider error details, when available. properties: name: type: string enum: - plaid description: Provider that returned the underlying error. errorCode: type: string description: Provider error code, when available. errorType: type: string description: Provider error type, when available. requestId: type: string description: Provider request ID for troubleshooting. required: - name additionalProperties: false required: - supportId additionalProperties: false required: - code - detail - status - meta additionalProperties: false required: - errors additionalProperties: false examples: default: summary: Default value: errors: - code: not_found detail: The requested resource was not found. status: '404' meta: supportId: req_a1b2c3d4e5f6 '409': description: Conflict content: application/json: schema: type: object properties: errors: type: array minItems: 1 items: type: object properties: code: type: string description: Stable lower-snake-case public error code. detail: type: string description: Safe user-facing error detail. status: type: string description: HTTP status code as a string. source: type: object description: Location of the invalid request value. properties: pointer: type: string description: JSON Pointer to the invalid request value. parameter: type: string description: Name of the invalid query parameter. header: type: string description: Name of the invalid request header. additionalProperties: false meta: type: object description: >- Additional error context, including support and provider details when available. properties: supportId: type: string description: Request/support ID for troubleshooting. limitScope: type: string enum: - merchant - program description: >- Which family of acquiring limit refused the payment. Thresholds and usage are never disclosed. connectionStatus: type: string enum: - login_required - disconnected description: >- External account connection state when the error is repairable by relinking. provider: type: object description: Provider error details, when available. properties: name: type: string enum: - plaid description: Provider that returned the underlying error. errorCode: type: string description: Provider error code, when available. errorType: type: string description: Provider error type, when available. requestId: type: string description: Provider request ID for troubleshooting. required: - name additionalProperties: false required: - supportId additionalProperties: false required: - code - detail - status - meta additionalProperties: false required: - errors additionalProperties: false examples: default: summary: Default value: errors: - code: conflict detail: The request conflicts with the current resource state. status: '409' meta: supportId: req_a1b2c3d4e5f6 '422': description: >- Validation Error. The response contains one error object for each invalid request value. content: application/json: schema: type: object properties: errors: type: array minItems: 1 items: type: object properties: code: type: string description: Stable lower-snake-case public error code. detail: type: string description: Safe user-facing error detail. status: type: string description: HTTP status code as a string. source: type: object description: Location of the invalid request value. properties: pointer: type: string description: JSON Pointer to the invalid request value. parameter: type: string description: Name of the invalid query parameter. header: type: string description: Name of the invalid request header. additionalProperties: false meta: type: object description: >- Additional error context, including support and provider details when available. properties: supportId: type: string description: Request/support ID for troubleshooting. limitScope: type: string enum: - merchant - program description: >- Which family of acquiring limit refused the payment. Thresholds and usage are never disclosed. connectionStatus: type: string enum: - login_required - disconnected description: >- External account connection state when the error is repairable by relinking. provider: type: object description: Provider error details, when available. properties: name: type: string enum: - plaid description: Provider that returned the underlying error. errorCode: type: string description: Provider error code, when available. errorType: type: string description: Provider error type, when available. requestId: type: string description: Provider request ID for troubleshooting. required: - name additionalProperties: false required: - supportId additionalProperties: false required: - code - detail - status - meta additionalProperties: false required: - errors additionalProperties: false examples: default: summary: Default value: errors: - code: invalid_value detail: 'Too big: expected string to have <=80 characters' status: '422' source: pointer: /data/attributes/description meta: supportId: req_a1b2c3d4e5f6 '428': description: Precondition Required content: application/json: schema: type: object properties: errors: type: array minItems: 1 items: type: object properties: code: type: string description: Stable lower-snake-case public error code. detail: type: string description: Safe user-facing error detail. status: type: string description: HTTP status code as a string. source: type: object description: Location of the invalid request value. properties: pointer: type: string description: JSON Pointer to the invalid request value. parameter: type: string description: Name of the invalid query parameter. header: type: string description: Name of the invalid request header. additionalProperties: false meta: type: object description: >- Additional error context, including support and provider details when available. properties: supportId: type: string description: Request/support ID for troubleshooting. limitScope: type: string enum: - merchant - program description: >- Which family of acquiring limit refused the payment. Thresholds and usage are never disclosed. connectionStatus: type: string enum: - login_required - disconnected description: >- External account connection state when the error is repairable by relinking. provider: type: object description: Provider error details, when available. properties: name: type: string enum: - plaid description: Provider that returned the underlying error. errorCode: type: string description: Provider error code, when available. errorType: type: string description: Provider error type, when available. requestId: type: string description: Provider request ID for troubleshooting. required: - name additionalProperties: false required: - supportId additionalProperties: false required: - code - detail - status - meta additionalProperties: false required: - errors additionalProperties: false examples: default: summary: Default value: errors: - code: mfa_required detail: MFA verification required status: '428' meta: supportId: req_a1b2c3d4e5f6 '429': description: Too Many Requests content: application/json: schema: type: object properties: errors: type: array minItems: 1 items: type: object properties: code: type: string description: Stable lower-snake-case public error code. detail: type: string description: Safe user-facing error detail. status: type: string description: HTTP status code as a string. source: type: object description: Location of the invalid request value. properties: pointer: type: string description: JSON Pointer to the invalid request value. parameter: type: string description: Name of the invalid query parameter. header: type: string description: Name of the invalid request header. additionalProperties: false meta: type: object description: >- Additional error context, including support and provider details when available. properties: supportId: type: string description: Request/support ID for troubleshooting. limitScope: type: string enum: - merchant - program description: >- Which family of acquiring limit refused the payment. Thresholds and usage are never disclosed. connectionStatus: type: string enum: - login_required - disconnected description: >- External account connection state when the error is repairable by relinking. provider: type: object description: Provider error details, when available. properties: name: type: string enum: - plaid description: Provider that returned the underlying error. errorCode: type: string description: Provider error code, when available. errorType: type: string description: Provider error type, when available. requestId: type: string description: Provider request ID for troubleshooting. required: - name additionalProperties: false required: - supportId additionalProperties: false required: - code - detail - status - meta additionalProperties: false required: - errors additionalProperties: false examples: default: summary: Default value: errors: - code: rate_limited detail: Too many requests. Please try again later. status: '429' meta: supportId: req_a1b2c3d4e5f6 headers: Retry-After: description: Seconds to wait before retrying. schema: type: integer X-RateLimit-Limit: description: Maximum requests allowed per window. schema: type: integer X-RateLimit-Remaining: description: Requests remaining in current window. schema: type: integer X-RateLimit-Reset: description: Unix timestamp when rate limit resets. schema: type: integer '500': description: Internal Server Error content: application/json: schema: type: object properties: errors: type: array minItems: 1 items: type: object properties: code: type: string description: Stable lower-snake-case public error code. detail: type: string description: Safe user-facing error detail. status: type: string description: HTTP status code as a string. source: type: object description: Location of the invalid request value. properties: pointer: type: string description: JSON Pointer to the invalid request value. parameter: type: string description: Name of the invalid query parameter. header: type: string description: Name of the invalid request header. additionalProperties: false meta: type: object description: >- Additional error context, including support and provider details when available. properties: supportId: type: string description: Request/support ID for troubleshooting. limitScope: type: string enum: - merchant - program description: >- Which family of acquiring limit refused the payment. Thresholds and usage are never disclosed. connectionStatus: type: string enum: - login_required - disconnected description: >- External account connection state when the error is repairable by relinking. provider: type: object description: Provider error details, when available. properties: name: type: string enum: - plaid description: Provider that returned the underlying error. errorCode: type: string description: Provider error code, when available. errorType: type: string description: Provider error type, when available. requestId: type: string description: Provider request ID for troubleshooting. required: - name additionalProperties: false required: - supportId additionalProperties: false required: - code - detail - status - meta additionalProperties: false required: - errors additionalProperties: false examples: default: summary: Default value: errors: - code: server_error detail: Something went wrong. status: '500' meta: supportId: req_a1b2c3d4e5f6 '501': description: Not Implemented content: application/json: schema: type: object properties: errors: type: array minItems: 1 items: type: object properties: code: type: string description: Stable lower-snake-case public error code. detail: type: string description: Safe user-facing error detail. status: type: string description: HTTP status code as a string. source: type: object description: Location of the invalid request value. properties: pointer: type: string description: JSON Pointer to the invalid request value. parameter: type: string description: Name of the invalid query parameter. header: type: string description: Name of the invalid request header. additionalProperties: false meta: type: object description: >- Additional error context, including support and provider details when available. properties: supportId: type: string description: Request/support ID for troubleshooting. limitScope: type: string enum: - merchant - program description: >- Which family of acquiring limit refused the payment. Thresholds and usage are never disclosed. connectionStatus: type: string enum: - login_required - disconnected description: >- External account connection state when the error is repairable by relinking. provider: type: object description: Provider error details, when available. properties: name: type: string enum: - plaid description: Provider that returned the underlying error. errorCode: type: string description: Provider error code, when available. errorType: type: string description: Provider error type, when available. requestId: type: string description: Provider request ID for troubleshooting. required: - name additionalProperties: false required: - supportId additionalProperties: false required: - code - detail - status - meta additionalProperties: false required: - errors additionalProperties: false examples: default: summary: Default value: errors: - code: not_implemented detail: This operation is not available. status: '501' meta: supportId: req_a1b2c3d4e5f6 '502': description: Bad Gateway content: application/json: schema: type: object properties: errors: type: array minItems: 1 items: type: object properties: code: type: string description: Stable lower-snake-case public error code. detail: type: string description: Safe user-facing error detail. status: type: string description: HTTP status code as a string. source: type: object description: Location of the invalid request value. properties: pointer: type: string description: JSON Pointer to the invalid request value. parameter: type: string description: Name of the invalid query parameter. header: type: string description: Name of the invalid request header. additionalProperties: false meta: type: object description: >- Additional error context, including support and provider details when available. properties: supportId: type: string description: Request/support ID for troubleshooting. limitScope: type: string enum: - merchant - program description: >- Which family of acquiring limit refused the payment. Thresholds and usage are never disclosed. connectionStatus: type: string enum: - login_required - disconnected description: >- External account connection state when the error is repairable by relinking. provider: type: object description: Provider error details, when available. properties: name: type: string enum: - plaid description: Provider that returned the underlying error. errorCode: type: string description: Provider error code, when available. errorType: type: string description: Provider error type, when available. requestId: type: string description: Provider request ID for troubleshooting. required: - name additionalProperties: false required: - supportId additionalProperties: false required: - code - detail - status - meta additionalProperties: false required: - errors additionalProperties: false examples: default: summary: Default value: errors: - code: bad_gateway detail: >- We couldn't complete that request because one of Natural's services returned an unexpected response. Please try again. status: '502' meta: supportId: req_a1b2c3d4e5f6 '503': description: Service Unavailable content: application/json: schema: type: object properties: errors: type: array minItems: 1 items: type: object properties: code: type: string description: Stable lower-snake-case public error code. detail: type: string description: Safe user-facing error detail. status: type: string description: HTTP status code as a string. source: type: object description: Location of the invalid request value. properties: pointer: type: string description: JSON Pointer to the invalid request value. parameter: type: string description: Name of the invalid query parameter. header: type: string description: Name of the invalid request header. additionalProperties: false meta: type: object description: >- Additional error context, including support and provider details when available. properties: supportId: type: string description: Request/support ID for troubleshooting. limitScope: type: string enum: - merchant - program description: >- Which family of acquiring limit refused the payment. Thresholds and usage are never disclosed. connectionStatus: type: string enum: - login_required - disconnected description: >- External account connection state when the error is repairable by relinking. provider: type: object description: Provider error details, when available. properties: name: type: string enum: - plaid description: Provider that returned the underlying error. errorCode: type: string description: Provider error code, when available. errorType: type: string description: Provider error type, when available. requestId: type: string description: Provider request ID for troubleshooting. required: - name additionalProperties: false required: - supportId additionalProperties: false required: - code - detail - status - meta additionalProperties: false required: - errors additionalProperties: false examples: default: summary: Default value: errors: - code: service_unavailable detail: The service is temporarily unavailable. status: '503' meta: supportId: req_a1b2c3d4e5f6 security: - HTTPBearer: [] components: securitySchemes: HTTPBearer: type: http scheme: bearer description: >- Bearer authentication: send your API key, agent key, or OAuth access token as `Authorization: Bearer `. ````