> ## 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. # Fulfill payment request > Fulfill an open payment request from inside the authenticated app. ## OpenAPI ````yaml /api-reference/openapi.json post /payment-requests/{paymentRequestId}/fulfill 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.co` Agents and coding assistants should prefer the hosted MCP server at `https://mcp.natural.co` 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.co servers: - url: https://api.natural.co description: Production security: [] tags: - name: Agents description: Agent management - name: Customers description: Customer management - name: Counterparties description: Counterparty management - name: Payments description: Payment operations - name: Transactions description: Transaction activity and history operations - name: Transfers description: Deposit and withdrawal operations - name: PaymentRequests description: Payment-request management - name: Approvals description: Approval review operations - name: Invitations description: Party invitation management - name: Identity description: Caller identity introspection - name: Parties description: Party and organization management - name: Wallets description: Wallet balance, deposits, withdrawals, and external accounts - name: External Accounts description: Linked external bank 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 access paths: /payment-requests/{paymentRequestId}/fulfill: post: tags: - PaymentRequests summary: Fulfill payment request description: Fulfill an open payment request from inside the authenticated app. operationId: paymentRequests.fulfill parameters: - name: paymentRequestId in: path required: true schema: type: string pattern: ^prq_[0-9a-f]{32}$ - name: Idempotency-Key in: header required: true schema: type: string description: >- Unique key for idempotent request handling. If a request with the same key was already processed, the original response is returned. - name: X-Agent-ID in: header required: false schema: anyOf: - type: string - type: 'null' description: Agent ID (agt_xxx) identifying which agent is making the request. - name: X-Instance-ID in: header required: false schema: anyOf: - type: string maxLength: 1024 - type: 'null' description: >- Required when X-Agent-ID is present. Session or conversation ID for agent observability. requestBody: required: true content: application/json: schema: type: object properties: partyId: type: string pattern: ^pty_[0-9a-f]{32}$ description: >- Effective payer party ID (pty_*) for delegated payment request fulfillment. data: type: object properties: attributes: type: object properties: paymentSource: anyOf: - type: object properties: type: type: string enum: - wallet walletId: type: string pattern: ^wal_[0-9a-f]{32}$ required: - type - walletId additionalProperties: false - type: object properties: type: type: string enum: - external_account externalAccountId: type: string pattern: ^eac_[0-9a-f]{32}$ required: - type - externalAccountId additionalProperties: false required: - paymentSource additionalProperties: false required: - attributes additionalProperties: false required: - data additionalProperties: false examples: default: summary: Default value: data: attributes: paymentSource: type: wallet walletId: wal_550e8400e29b41d4a716446655440000 responses: '200': description: Successful Response content: application/json: schema: type: object properties: data: type: object properties: type: type: string enum: - payment id: type: string pattern: ^pay_[0-9a-f]{32}$ attributes: type: object properties: amount: type: integer description: Amount in cents currency: type: string description: Currency code status: enum: - CREATED - PROCESSING - PENDING_CLAIM - IN_REVIEW - COMPLETED - FAILED - RETURNED - APPROVAL_DENIED - CANCELED type: string description: Payment status description: anyOf: - type: string - type: 'null' description: Payment description createdAt: type: string description: When this payment was created updatedAt: anyOf: - type: string - type: 'null' description: When this payment was last updated required: - amount - currency - status - description - createdAt - updatedAt additionalProperties: false title: PaymentAttributes description: Resource attributes relationships: type: object properties: sender: type: object properties: data: anyOf: - type: object properties: type: description: Resource type type: string enum: - party id: type: string pattern: ^pty_[0-9a-f]{32}$ required: - type - id additionalProperties: false title: ResourceIdentifier description: Related resource identifier - type: 'null' required: - data additionalProperties: false title: NullableToOneRelationship description: >- Party that initiated the payment, when the sender is on Natural. recipient: type: object properties: data: anyOf: - type: object properties: type: description: Resource type type: string enum: - party id: type: string pattern: ^pty_[0-9a-f]{32}$ required: - type - id additionalProperties: false title: ResourceIdentifier description: Related resource identifier - type: 'null' required: - data additionalProperties: false title: NullableToOneRelationship description: Recipient party for this payment, when known. recipientAgent: type: object properties: data: anyOf: - type: object properties: type: description: Resource type type: string enum: - agent id: type: string pattern: ^agt_[0-9a-f]{32}$ required: - type - id additionalProperties: false title: ResourceIdentifier description: Related resource identifier - type: 'null' required: - data additionalProperties: false title: NullableToOneRelationship description: >- Recipient agent when the caller addressed an agent ID. Null otherwise, including when the recipient was addressed as an email, phone, or party ID. transaction: type: object properties: data: anyOf: - type: object properties: type: description: Resource type type: string enum: - transaction id: type: string required: - type - id additionalProperties: false title: ResourceIdentifier description: Related resource identifier - type: 'null' required: - data additionalProperties: false title: NullableToOneRelationship description: >- Sender-side transaction row for this payment, when available. paymentRequest: type: object properties: data: anyOf: - type: object properties: type: description: Resource type type: string enum: - paymentRequest id: type: string pattern: ^prq_[0-9a-f]{32}$ required: - type - id additionalProperties: false title: ResourceIdentifier description: Related resource identifier - type: 'null' required: - data additionalProperties: false title: NullableToOneRelationship description: >- Payment request that produced this payment, when applicable. required: - sender - recipient - recipientAgent - transaction - paymentRequest additionalProperties: false title: PaymentRelationships description: Resource relationships required: - type - id - attributes - relationships additionalProperties: false title: PaymentResource required: - data additionalProperties: false examples: default: summary: Default value: data: type: payment id: pay_550e8400e29b41d4a716446655440000 attributes: amount: 2500 currency: USD status: PROCESSING description: Invoice 7 createdAt: '2026-04-15T00:00:00.000Z' updatedAt: '2026-04-15T00:00:00.000Z' relationships: sender: data: type: party id: pty_550e8400e29b41d4a716446655440000 recipient: data: type: party id: pty_019cd1798d617f65a79cb965dda9eac3 recipientAgent: data: null transaction: data: null paymentRequest: data: type: paymentRequest id: prq_550e8400e29b41d4a716446655440000 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 parameter: type: string header: type: string additionalProperties: false meta: type: object description: >- Error metadata. Public responses include supportId by default and may include allowlisted provider recovery metadata. properties: supportId: type: string description: Request/support ID for troubleshooting connectionStatus: type: string enum: - login_required - disconnected description: >- External account connection state when the error is repairable by relinking provider: type: object 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: A request value is invalid. 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 parameter: type: string header: type: string additionalProperties: false meta: type: object description: >- Error metadata. Public responses include supportId by default and may include allowlisted provider recovery metadata. properties: supportId: type: string description: Request/support ID for troubleshooting connectionStatus: type: string enum: - login_required - disconnected description: >- External account connection state when the error is repairable by relinking provider: type: object 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 parameter: type: string header: type: string additionalProperties: false meta: type: object description: >- Error metadata. Public responses include supportId by default and may include allowlisted provider recovery metadata. properties: supportId: type: string description: Request/support ID for troubleshooting connectionStatus: type: string enum: - login_required - disconnected description: >- External account connection state when the error is repairable by relinking provider: type: object 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 parameter: type: string header: type: string additionalProperties: false meta: type: object description: >- Error metadata. Public responses include supportId by default and may include allowlisted provider recovery metadata. properties: supportId: type: string description: Request/support ID for troubleshooting connectionStatus: type: string enum: - login_required - disconnected description: >- External account connection state when the error is repairable by relinking provider: type: object 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 parameter: type: string header: type: string additionalProperties: false meta: type: object description: >- Error metadata. Public responses include supportId by default and may include allowlisted provider recovery metadata. properties: supportId: type: string description: Request/support ID for troubleshooting connectionStatus: type: string enum: - login_required - disconnected description: >- External account connection state when the error is repairable by relinking provider: type: object 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 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 parameter: type: string header: type: string additionalProperties: false meta: type: object description: >- Error metadata. Public responses include supportId by default and may include allowlisted provider recovery metadata. properties: supportId: type: string description: Request/support ID for troubleshooting connectionStatus: type: string enum: - login_required - disconnected description: >- External account connection state when the error is repairable by relinking provider: type: object 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: 'email: Invalid email address' status: '422' source: pointer: /data/attributes/email 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 parameter: type: string header: type: string additionalProperties: false meta: type: object description: >- Error metadata. Public responses include supportId by default and may include allowlisted provider recovery metadata. properties: supportId: type: string description: Request/support ID for troubleshooting connectionStatus: type: string enum: - login_required - disconnected description: >- External account connection state when the error is repairable by relinking provider: type: object 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 parameter: type: string header: type: string additionalProperties: false meta: type: object description: >- Error metadata. Public responses include supportId by default and may include allowlisted provider recovery metadata. properties: supportId: type: string description: Request/support ID for troubleshooting connectionStatus: type: string enum: - login_required - disconnected description: >- External account connection state when the error is repairable by relinking provider: type: object 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 parameter: type: string header: type: string additionalProperties: false meta: type: object description: >- Error metadata. Public responses include supportId by default and may include allowlisted provider recovery metadata. properties: supportId: type: string description: Request/support ID for troubleshooting connectionStatus: type: string enum: - login_required - disconnected description: >- External account connection state when the error is repairable by relinking provider: type: object 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 parameter: type: string header: type: string additionalProperties: false meta: type: object description: >- Error metadata. Public responses include supportId by default and may include allowlisted provider recovery metadata. properties: supportId: type: string description: Request/support ID for troubleshooting connectionStatus: type: string enum: - login_required - disconnected description: >- External account connection state when the error is repairable by relinking provider: type: object 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 parameter: type: string header: type: string additionalProperties: false meta: type: object description: >- Error metadata. Public responses include supportId by default and may include allowlisted provider recovery metadata. properties: supportId: type: string description: Request/support ID for troubleshooting connectionStatus: type: string enum: - login_required - disconnected description: >- External account connection state when the error is repairable by relinking provider: type: object 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 parameter: type: string header: type: string additionalProperties: false meta: type: object description: >- Error metadata. Public responses include supportId by default and may include allowlisted provider recovery metadata. properties: supportId: type: string description: Request/support ID for troubleshooting connectionStatus: type: string enum: - login_required - disconnected description: >- External account connection state when the error is repairable by relinking provider: type: object 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 ````