openapi: 3.0.1
info:
  title: Mono Account Information Direct Debit API
  description: Specification of the Mono open-banking API. Mono lets businesses link customer bank accounts (Connect) to read transactions, statements, identity, income, and balance, and to collect payments via DirectPay one-time transfers and Direct Debit mandates. All requests are authenticated with the secret application key supplied in the mono-sec-key header. Monetary amounts are expressed in the lowest denomination of the currency (e.g. kobo for NGN).
  termsOfService: https://mono.co/legal
  contact:
    name: Mono Support
    url: https://docs.mono.co
    email: hi@mono.co
  version: '2.0'
servers:
- url: https://api.withmono.com
  description: Mono production API
security:
- monoSecKey: []
tags:
- name: Direct Debit
  description: Customers, mandates, balance inquiry, and recurring debits.
paths:
  /v2/customers:
    post:
      operationId: createCustomer
      tags:
      - Direct Debit
      summary: Create a customer
      description: Creates an individual or business customer record used for direct-debit mandates.
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CreateCustomerRequest'
      responses:
        '201':
          description: Customer created.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Customer'
        '401':
          $ref: '#/components/responses/Unauthorized'
    get:
      operationId: listCustomers
      tags:
      - Direct Debit
      summary: List customers
      description: Lists customers created on the account.
      parameters:
      - name: page
        in: query
        schema:
          type: integer
      responses:
        '200':
          description: Customer list.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/CustomerList'
        '401':
          $ref: '#/components/responses/Unauthorized'
  /v2/payments/initiate-mandate:
    post:
      operationId: initiateMandate
      tags:
      - Direct Debit
      summary: Initiate mandate authorisation
      description: Sets up a fixed or variable direct-debit mandate on a customer's bank account and returns a hosted authorisation link. Each mandate setup is a one-time authorization process.
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/InitiateMandateRequest'
      responses:
        '200':
          description: Mandate authorisation initiated.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/InitiateMandateResponse'
        '401':
          $ref: '#/components/responses/Unauthorized'
  /v3/payments/mandates/{id}/balance:
    get:
      operationId: mandateBalanceInquiry
      tags:
      - Direct Debit
      summary: Mandate balance inquiry
      description: Confirmation-of-funds check against a mandated account before initiating a debit.
      parameters:
      - $ref: '#/components/parameters/MandateId'
      responses:
        '200':
          description: Balance inquiry result.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Balance'
        '401':
          $ref: '#/components/responses/Unauthorized'
  /v3/payments/mandates/{id}/debit:
    post:
      operationId: debitMandate
      tags:
      - Direct Debit
      summary: Debit a mandate
      description: Debits a bank account that already has an approved direct-debit mandate.
      parameters:
      - $ref: '#/components/parameters/MandateId'
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/DebitMandateRequest'
      responses:
        '200':
          description: Debit submitted.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/PaymentStatus'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '404':
          $ref: '#/components/responses/NotFound'
components:
  schemas:
    Customer:
      type: object
      properties:
        status:
          type: string
        message:
          type: string
        data:
          type: object
          properties:
            id:
              type: string
            email:
              type: string
            phone:
              type: string
            first_name:
              type: string
            last_name:
              type: string
            type:
              type: string
    DebitMandateRequest:
      type: object
      required:
      - amount
      - reference
      properties:
        amount:
          type: integer
        reference:
          type: string
        narration:
          type: string
    Error:
      type: object
      properties:
        status:
          type: string
        message:
          type: string
    InitiateMandateRequest:
      type: object
      required:
      - amount
      - type
      - mandate_type
      - reference
      properties:
        amount:
          type: integer
        type:
          type: string
          example: recurring-debit
        method:
          type: string
          example: mandate
        mandate_type:
          type: string
          enum:
          - emandate
          - signed
          - gsm
        debit_type:
          type: string
          enum:
          - fixed
          - variable
        description:
          type: string
        reference:
          type: string
        redirect_url:
          type: string
        customer:
          type: object
          properties:
            id:
              type: string
        account_number:
          type: string
        bank_code:
          type: string
        start_date:
          type: string
        end_date:
          type: string
        meta:
          type: object
    PaymentStatus:
      type: object
      properties:
        status:
          type: string
        message:
          type: string
        data:
          type: object
          properties:
            id:
              type: string
            reference:
              type: string
            amount:
              type: integer
            status:
              type: string
              enum:
              - successful
              - failed
              - pending
              - abandoned
            currency:
              type: string
            created_at:
              type: string
              format: date-time
    InitiateMandateResponse:
      type: object
      properties:
        status:
          type: string
        message:
          type: string
        data:
          type: object
          properties:
            id:
              type: string
            mono_url:
              type: string
            mandate_type:
              type: string
            reference:
              type: string
            status:
              type: string
    CustomerList:
      type: object
      properties:
        status:
          type: string
        message:
          type: string
        data:
          type: array
          items:
            $ref: '#/components/schemas/Customer'
    CreateCustomerRequest:
      type: object
      properties:
        email:
          type: string
        phone:
          type: string
        address:
          type: string
        identity:
          type: object
          properties:
            type:
              type: string
            number:
              type: string
        type:
          type: string
          enum:
          - individual
          - business
        first_name:
          type: string
        last_name:
          type: string
        business_name:
          type: string
    Balance:
      type: object
      properties:
        status:
          type: string
        message:
          type: string
        data:
          type: object
          properties:
            id:
              type: string
            name:
              type: string
            account_number:
              type: string
            balance:
              type: integer
            currency:
              type: string
  responses:
    Unauthorized:
      description: Missing or invalid mono-sec-key.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    NotFound:
      description: Resource not found.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
  parameters:
    MandateId:
      name: id
      in: path
      required: true
      description: The direct-debit mandate id.
      schema:
        type: string
  securitySchemes:
    monoSecKey:
      type: apiKey
      in: header
      name: mono-sec-key
      description: Secret application key issued in the Mono dashboard.