Interswitch Payment Gateway API

openapi: 3.1.0
info:
  title: Interswitch Payment Gateway API
  description: |
    Server-to-server card payment APIs for PCI-DSS-licensed merchants — direct
    Card Payments, Hosted Fields tokenization, 3D Secure step-up, Google Pay,
    and Pay Bill payment-link generation. Authenticated with OAuth 2.0
    client_credentials via the Passport token service.
  version: '2024-01-01'
servers:
  - url: https://qa.interswitchng.com
    description: Sandbox / QA
  - url: https://saturn.interswitchng.com
    description: Production
security:
  - BearerAuth: []
tags:
  - name: Payments
    description: Direct card payment authorization
  - name: Hosted Fields
    description: Card data tokenization
  - name: Three-D Secure
    description: Step-up authentication
  - name: Payment Links
    description: Hosted payment link generation
paths:
  /paymentgateway/api/v1/payments:
    post:
      tags: [Payments]
      summary: Create Card Payment
      description: Authorize and capture a card payment using a tokenized or hosted-field-collected card.
      operationId: createCardPayment
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/PaymentRequest'
      responses:
        '200':
          description: Payment result.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/PaymentResponse'
  /paymentgateway/api/v1/payments/{paymentId}:
    get:
      tags: [Payments]
      summary: Get Payment
      operationId: getPayment
      parameters:
        - in: path
          name: paymentId
          required: true
          schema: { type: string }
      responses:
        '200':
          description: Payment details.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/PaymentResponse'
  /paymentgateway/api/v1/hosted-fields/sessions:
    post:
      tags: [Hosted Fields]
      summary: Create Hosted Fields Session
      description: Create a hosted-fields session so the browser can collect raw card data and POST it directly to Interswitch, keeping the merchant out of PCI scope.
      operationId: createHostedFieldsSession
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              required: [transactionRef, amount, currency]
              properties:
                transactionRef: { type: string }
                amount: { type: integer }
                currency: { type: string }
                redirectUrl: { type: string, format: uri }
      responses:
        '200':
          description: Session created.
          content:
            application/json:
              schema:
                type: object
                properties:
                  sessionId: { type: string }
                  hostedFieldsUrl: { type: string, format: uri }
                  expiresAt: { type: string, format: date-time }
  /paymentgateway/api/v1/three-d-secure/sessions:
    post:
      tags: [Three-D Secure]
      summary: Create 3D Secure Session
      operationId: createThreeDSecureSession
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              required: [paymentId, returnUrl]
              properties:
                paymentId: { type: string }
                returnUrl: { type: string, format: uri }
      responses:
        '200':
          description: Step-up redirect details.
          content:
            application/json:
              schema:
                type: object
                properties:
                  acsUrl: { type: string, format: uri }
                  pareq: { type: string }
                  md: { type: string }
  /paymentgateway/api/v1/payment-links:
    post:
      tags: [Payment Links]
      summary: Create Payment Link
      description: Create a hosted Pay Bill payment link the merchant can email, SMS, or share.
      operationId: createPaymentLink
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              required: [amount, currency, description]
              properties:
                amount: { type: integer }
                currency: { type: string }
                description: { type: string }
                customerEmail: { type: string, format: email }
                expiresAt: { type: string, format: date-time }
      responses:
        '201':
          description: Created.
          content:
            application/json:
              schema:
                type: object
                properties:
                  paymentLinkId: { type: string }
                  url: { type: string, format: uri }
                  status: { type: string }
components:
  securitySchemes:
    BearerAuth:
      type: http
      scheme: bearer
      description: Bearer token from `POST {passport}/passport/oauth/token?grant_type=client_credentials`.
  schemas:
    PaymentRequest:
      type: object
      required: [transactionRef, amount, currency, paymentMethod]
      properties:
        transactionRef: { type: string }
        amount: { type: integer, description: Minor currency units. }
        currency: { type: string }
        customerId: { type: string }
        customerEmail: { type: string, format: email }
        paymentMethod:
          type: object
          properties:
            type: { type: string, enum: [card, token, googlePay] }
            card:
              type: object
              properties:
                pan: { type: string }
                expiryMonth: { type: string }
                expiryYear: { type: string }
                cvv: { type: string }
            token: { type: string }
    PaymentResponse:
      type: object
      properties:
        paymentId: { type: string }
        status: { type: string }
        responseCode: { type: string }
        responseMessage: { type: string }
        amount: { type: integer }
        currency: { type: string }
        authCode: { type: string }
        retrievalReferenceNumber: { type: string }