Montran Instant Payments API

openapi: 3.2.0
info:
  title: Montran Gateway Instant Payments API
  description: The Montran Instant Payments Gateway (IPG) enables participants in an instant payments ecosystem to support high volumes of instant payments in a high availability 24x7 environment.
  version: 1.0.0
  contact:
    name: Montran Corporation
    url: https://www.montran.com/contact-us/
  license:
    name: Proprietary
    url: https://www.montran.com/terms-conditions/
  x-logo:
    url: https://www.montran.com/logo.png
servers:
- url: https://api.montran.com/ipg/v1
  description: Montran Instant Payments Gateway API Server
security:
- oauth2:
  - aisp
  - pisp
- bearerAuth: []
tags:
- name: Instant Payments
  description: Real-time instant payment processing with guaranteed end-to-end latency of a few seconds
paths:
  /payments/instant:
    post:
      operationId: initiateInstantPayment
      summary: Montran Initiate an instant payment
      description: Initiates a real-time instant payment with guaranteed end-to-end processing latency of a few seconds. The payment is processed using ISO 20022 pacs.008 FIToFICustomerCreditTransfer messaging. Supports credit transfers across instant payment schemes. Returns the payment status synchronously, including confirmation or rejection.
      tags:
      - Instant Payments
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/InstantPaymentRequest'
      responses:
        '201':
          description: Instant payment successfully processed
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/InstantPaymentResponse'
        '400':
          $ref: '#/components/responses/BadRequest'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '403':
          $ref: '#/components/responses/Forbidden'
        '422':
          $ref: '#/components/responses/UnprocessableEntity'
        '500':
          $ref: '#/components/responses/InternalServerError'
        '503':
          description: Service temporarily unavailable
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
  /payments/instant/{paymentId}:
    get:
      operationId: getInstantPayment
      summary: Montran Get instant payment details
      description: Retrieves the full details and current status of a specific instant payment. Returns ISO 20022 pacs.002 status information including acceptance or rejection reason codes.
      tags:
      - Instant Payments
      parameters:
      - $ref: '#/components/parameters/PaymentIdParam'
      responses:
        '200':
          description: Successfully retrieved instant payment details
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/InstantPaymentDetail'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '404':
          $ref: '#/components/responses/NotFound'
        '500':
          $ref: '#/components/responses/InternalServerError'
  /payments/instant/{paymentId}/return:
    post:
      operationId: returnInstantPayment
      summary: Montran Return an instant payment
      description: Initiates the return of a previously received instant payment. Uses ISO 20022 pacs.004 PaymentReturn messaging. The return must specify a valid reason code.
      tags:
      - Instant Payments
      parameters:
      - $ref: '#/components/parameters/PaymentIdParam'
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/PaymentReturnRequest'
      responses:
        '200':
          description: Payment return successfully initiated
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/PaymentReturnResponse'
        '400':
          $ref: '#/components/responses/BadRequest'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '404':
          $ref: '#/components/responses/NotFound'
        '409':
          description: Payment cannot be returned in its current state
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '500':
          $ref: '#/components/responses/InternalServerError'
  /payments/bulk:
    post:
      operationId: submitBulkPayment
      summary: Montran Submit a bulk payment
      description: Submits a batch of instant payments for processing. Each payment in the batch is processed individually in real-time. Supports high-volume use cases such as salary payments and batch collections.
      tags:
      - Instant Payments
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/BulkPaymentRequest'
      responses:
        '202':
          description: Bulk payment accepted for processing
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/BulkPaymentResponse'
        '400':
          $ref: '#/components/responses/BadRequest'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '422':
          $ref: '#/components/responses/UnprocessableEntity'
        '500':
          $ref: '#/components/responses/InternalServerError'
components:
  schemas:
    PaymentReturnRequest:
      type: object
      description: Payment return request using ISO 20022 pacs.004 PaymentReturn
      required:
      - reasonCode
      properties:
        reasonCode:
          type: string
          description: Return reason code
          enum:
          - AC01
          - AC04
          - AC06
          - AG01
          - AM05
          - BE04
          - DNOR
          - FOCR
          - MD01
          - MS02
          - RR01
        additionalInformation:
          type: string
          description: Additional return reason information
    FinancialInstitution:
      type: object
      description: Financial institution identification
      properties:
        bic:
          type: string
          description: Bank Identifier Code (SWIFT/BIC)
          pattern: ^[A-Z]{4}[A-Z]{2}[A-Z0-9]{2}([A-Z0-9]{3})?$
        name:
          type: string
          description: Name of the financial institution
    InstantPaymentDetail:
      type: object
      description: Full instant payment details
      properties:
        paymentId:
          type: string
        messageId:
          type: string
        endToEndId:
          type: string
        transactionId:
          type: string
        status:
          type: string
          enum:
          - ACCP
          - ACSC
          - ACSP
          - RJCT
          - CANC
          - RTND
        debtorName:
          type: string
        debtorAccount:
          $ref: '#/components/schemas/AccountIdentification'
        debtorAgent:
          $ref: '#/components/schemas/FinancialInstitution'
        creditorName:
          type: string
        creditorAccount:
          $ref: '#/components/schemas/AccountIdentification'
        creditorAgent:
          $ref: '#/components/schemas/FinancialInstitution'
        amount:
          type: number
          format: double
        currency:
          type: string
        remittanceInformation:
          type: string
        reasonCode:
          type: string
        settlementDate:
          type: string
          format: date
        acceptanceDateTime:
          type: string
          format: date-time
        createdAt:
          type: string
          format: date-time
    BulkPaymentRequest:
      type: object
      description: Bulk payment submission request
      required:
      - payments
      properties:
        batchId:
          type: string
          description: Client-assigned batch identifier
        numberOfTransactions:
          type: integer
          description: Number of payments in the batch
        controlSum:
          type: number
          format: double
          description: Sum of all payment amounts for validation
        payments:
          type: array
          description: List of instant payment requests
          items:
            $ref: '#/components/schemas/InstantPaymentRequest'
          minItems: 1
    InstantPaymentResponse:
      type: object
      description: Response for an instant payment including real-time status
      properties:
        paymentId:
          type: string
          description: Unique payment identifier
        messageId:
          type: string
          description: Message identification
        endToEndId:
          type: string
          description: End-to-end identification
        transactionId:
          type: string
          description: Transaction identification
        status:
          type: string
          description: Payment processing status (ISO 20022 status codes)
          enum:
          - ACCP
          - ACSC
          - ACSP
          - RJCT
        reasonCode:
          type: string
          description: Rejection reason code if status is RJCT
        settlementDate:
          type: string
          format: date
          description: Settlement date
        acceptanceDateTime:
          type: string
          format: date-time
          description: Timestamp of payment acceptance
    BulkPaymentResponse:
      type: object
      description: Response for a bulk payment submission
      properties:
        bulkPaymentId:
          type: string
          description: Unique bulk payment identifier
        batchId:
          type: string
          description: Client batch identifier
        status:
          type: string
          enum:
          - ACCEPTED
          - PARTIALLY_ACCEPTED
          - REJECTED
        acceptedCount:
          type: integer
          description: Number of accepted payments
        rejectedCount:
          type: integer
          description: Number of rejected payments
        paymentResults:
          type: array
          items:
            type: object
            properties:
              index:
                type: integer
                description: Index of the payment in the original batch
              paymentId:
                type: string
              status:
                type: string
                enum:
                - ACCP
                - RJCT
              reasonCode:
                type: string
    Error:
      type: object
      description: Standard error response
      required:
      - code
      - message
      properties:
        code:
          type: string
          description: Error code
        message:
          type: string
          description: Human-readable error message
        details:
          type: array
          items:
            type: object
            properties:
              field:
                type: string
              message:
                type: string
    InstantPaymentRequest:
      type: object
      description: Instant payment initiation request using ISO 20022 pacs.008 FIToFICustomerCreditTransfer structure
      required:
      - debtorAccount
      - creditorAccount
      - amount
      - currency
      properties:
        messageId:
          type: string
          description: Unique message identification
        endToEndId:
          type: string
          description: End-to-end identification assigned by the initiating party
        transactionId:
          type: string
          description: Unique transaction identification
        debtorName:
          type: string
          description: Name of the debtor (payer)
        debtorAccount:
          $ref: '#/components/schemas/AccountIdentification'
        debtorAgent:
          $ref: '#/components/schemas/FinancialInstitution'
        creditorName:
          type: string
          description: Name of the creditor (payee)
        creditorAccount:
          $ref: '#/components/schemas/AccountIdentification'
        creditorAgent:
          $ref: '#/components/schemas/FinancialInstitution'
        amount:
          type: number
          format: double
          description: Payment amount
          minimum: 0.01
        currency:
          type: string
          description: ISO 4217 currency code
          pattern: ^[A-Z]{3}$
        remittanceInformation:
          type: string
          description: Remittance information or payment reference
        purpose:
          type: string
          description: Purpose code for the payment
        chargeBearer:
          type: string
          enum:
          - SLEV
    PaymentReturnResponse:
      type: object
      description: Response for a payment return
      properties:
        returnId:
          type: string
          description: Unique return identifier
        originalPaymentId:
          type: string
          description: Original payment identifier
        status:
          type: string
          enum:
          - PROCESSED
          - REJECTED
        processedAt:
          type: string
          format: date-time
    AccountIdentification:
      type: object
      description: Account identification using IBAN or proprietary identifier
      properties:
        iban:
          type: string
          description: International Bank Account Number
          pattern: ^[A-Z]{2}[0-9]{2}[A-Z0-9]{4,30}$
        accountNumber:
          type: string
          description: Proprietary account number
        currency:
          type: string
          description: Account currency (ISO 4217)
          pattern: ^[A-Z]{3}$
  responses:
    UnprocessableEntity:
      description: Request validation failed
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    Forbidden:
      description: Insufficient permissions or invalid consent
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    NotFound:
      description: Requested resource not found
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    InternalServerError:
      description: Internal server error
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    BadRequest:
      description: Bad request - invalid parameters or malformed request
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    Unauthorized:
      description: Authentication required or credentials invalid
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
  parameters:
    PaymentIdParam:
      name: paymentId
      in: path
      required: true
      description: Unique identifier of the payment
      schema:
        type: string
  securitySchemes:
    oauth2:
      type: oauth2
      description: OAuth 2.0 authorization for PSD2 AISP/PISP access
      flows:
        authorizationCode:
          authorizationUrl: https://auth.montran.com/oauth2/authorize
          tokenUrl: https://auth.montran.com/oauth2/token
          scopes:
            aisp: Account Information Service Provider access
            pisp: Payment Initiation Service Provider access
    bearerAuth:
      type: http
      scheme: bearer
      bearerFormat: JWT
      description: JWT bearer token authentication
externalDocs:
  description: Montran Instant Payments Gateway Documentation
  url: https://www.montran.com/solutions/instant-payments-gateway/