openapi: 3.0.1
info:
  title: Mono 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: Account Linking
    description: Initiate Connect account linking and exchange a code for an account id.
  - name: Account Information
    description: Account details and balance for a linked account.
  - name: Transactions and Statements
    description: Transactions and bank statements for a linked account.
  - name: Identity and Income
    description: Identity verification and income signals for a linked account.
  - name: DirectPay
    description: One-time bank-to-bank payments.
  - name: Direct Debit
    description: Customers, mandates, balance inquiry, and recurring debits.
paths:
  /v2/accounts/initiate:
    post:
      operationId: initiateAccountLinking
      tags:
        - Account Linking
      summary: Initiate account linking
      description: >-
        Starts a Mono Connect account-linking session and returns a hosted
        link that instantiates the Connect widget for the customer to
        authorize access to their bank account.
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/InitiateAccountRequest'
      responses:
        '200':
          description: Account-linking session created.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/InitiateAccountResponse'
        '401':
          $ref: '#/components/responses/Unauthorized'
  /v2/accounts/auth:
    post:
      operationId: exchangeToken
      tags:
        - Account Linking
      summary: Exchange token (auth)
      description: >-
        Exchanges the short-lived authorization code returned by the Connect
        widget for a persistent account id used to query account data. The
        authorization code expires after 10 minutes.
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/ExchangeTokenRequest'
      responses:
        '200':
          description: Account id returned.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ExchangeTokenResponse'
        '401':
          $ref: '#/components/responses/Unauthorized'
  /v2/accounts/{id}:
    get:
      operationId: getAccountDetails
      tags:
        - Account Information
      summary: Get account details
      description: Retrieves account holder, institution, and balance details for a linked account.
      parameters:
        - $ref: '#/components/parameters/AccountId'
      responses:
        '200':
          description: Account details.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/AccountDetails'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '404':
          $ref: '#/components/responses/NotFound'
  /v2/accounts/{id}/balance:
    get:
      operationId: getAccountBalance
      tags:
        - Account Information
      summary: Get account balance
      description: Returns the near-real-time balance for a linked account.
      parameters:
        - $ref: '#/components/parameters/AccountId'
      responses:
        '200':
          description: Account balance.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Balance'
        '401':
          $ref: '#/components/responses/Unauthorized'
  /v2/accounts/{id}/transactions:
    get:
      operationId: getAccountTransactions
      tags:
        - Transactions and Statements
      summary: Get transactions
      description: >-
        Lists money-in and money-out transactions for a linked account, with
        optional filters for date range, type, narration, and pagination.
      parameters:
        - $ref: '#/components/parameters/AccountId'
        - name: start
          in: query
          description: Start date (DD-MM-YYYY) of the transaction window.
          schema:
            type: string
        - name: end
          in: query
          description: End date (DD-MM-YYYY) of the transaction window.
          schema:
            type: string
        - name: type
          in: query
          description: Filter by transaction type.
          schema:
            type: string
            enum: [debit, credit]
        - name: narration
          in: query
          description: Filter by transaction narration substring.
          schema:
            type: string
        - name: paginate
          in: query
          description: Whether to paginate the results.
          schema:
            type: boolean
        - name: page
          in: query
          description: Page number when pagination is enabled.
          schema:
            type: integer
      responses:
        '200':
          description: Transaction list.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/TransactionList'
        '401':
          $ref: '#/components/responses/Unauthorized'
  /v2/accounts/{id}/statement:
    get:
      operationId: getAccountStatement
      tags:
        - Transactions and Statements
      summary: Get bank statement
      description: >-
        Retrieves the account holder's bank statement. Returns JSON by
        default; set output=pdf to generate a downloadable PDF statement.
      parameters:
        - $ref: '#/components/parameters/AccountId'
        - name: period
          in: query
          description: Statement period, e.g. last6months.
          schema:
            type: string
        - name: output
          in: query
          description: Response format.
          schema:
            type: string
            enum: [json, pdf]
      responses:
        '200':
          description: Statement data or PDF job reference.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Statement'
        '401':
          $ref: '#/components/responses/Unauthorized'
  /v2/accounts/{id}/identity:
    get:
      operationId: getAccountIdentity
      tags:
        - Identity and Income
      summary: Get identity
      description: Returns identity details (name, phone, BVN, date of birth) for a linked account holder.
      parameters:
        - $ref: '#/components/parameters/AccountId'
      responses:
        '200':
          description: Identity details.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Identity'
        '401':
          $ref: '#/components/responses/Unauthorized'
  /v2/accounts/{id}/income:
    get:
      operationId: getAccountIncome
      tags:
        - Identity and Income
      summary: Get income
      description: Returns income signals such as average monthly income, estimated salary, and income sources.
      parameters:
        - $ref: '#/components/parameters/AccountId'
      responses:
        '200':
          description: Income signals.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Income'
        '401':
          $ref: '#/components/responses/Unauthorized'
  /v2/accounts/{id}/unlink:
    post:
      operationId: unlinkAccount
      tags:
        - Account Information
      summary: Unlink account
      description: Unlinks a previously linked account, revoking further data access.
      parameters:
        - $ref: '#/components/parameters/AccountId'
      responses:
        '200':
          description: Account unlinked.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/StatusMessage'
        '401':
          $ref: '#/components/responses/Unauthorized'
  /v2/payments/initiate:
    post:
      operationId: initiatePayment
      tags:
        - DirectPay
      summary: Initiate DirectPay payment
      description: >-
        Initiates a one-time bank-to-bank DirectPay payment and returns a
        hosted payment link and reference for the customer to authorize.
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/InitiatePaymentRequest'
      responses:
        '200':
          description: Payment initiated.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/InitiatePaymentResponse'
        '401':
          $ref: '#/components/responses/Unauthorized'
  /v2/payments/verify/{reference}:
    get:
      operationId: verifyPayment
      tags:
        - DirectPay
      summary: Verify DirectPay payment
      description: Verifies the status of a DirectPay payment by its transaction reference.
      parameters:
        - name: reference
          in: path
          required: true
          description: The payment transaction reference.
          schema:
            type: string
      responses:
        '200':
          description: Payment status.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/PaymentStatus'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '404':
          $ref: '#/components/responses/NotFound'
  /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:
  securitySchemes:
    monoSecKey:
      type: apiKey
      in: header
      name: mono-sec-key
      description: Secret application key issued in the Mono dashboard.
  parameters:
    AccountId:
      name: id
      in: path
      required: true
      description: The linked account id returned by the exchange-token endpoint.
      schema:
        type: string
    MandateId:
      name: id
      in: path
      required: true
      description: The direct-debit mandate id.
      schema:
        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'
  schemas:
    InitiateAccountRequest:
      type: object
      properties:
        customer:
          type: object
          properties:
            name:
              type: string
            email:
              type: string
        meta:
          type: object
          properties:
            ref:
              type: string
        scope:
          type: string
          example: auth
        redirect_url:
          type: string
    InitiateAccountResponse:
      type: object
      properties:
        status:
          type: string
        message:
          type: string
        data:
          type: object
          properties:
            mono_url:
              type: string
            customer:
              type: string
            meta:
              type: object
    ExchangeTokenRequest:
      type: object
      required:
        - code
      properties:
        code:
          type: string
          description: The authorization code returned by the Connect widget.
    ExchangeTokenResponse:
      type: object
      properties:
        id:
          type: string
          description: The persistent account id.
    AccountDetails:
      type: object
      properties:
        meta:
          type: object
          properties:
            data_status:
              type: string
            auth_method:
              type: string
        account:
          type: object
          properties:
            id:
              type: string
            name:
              type: string
            currency:
              type: string
            type:
              type: string
            account_number:
              type: string
            balance:
              type: integer
            bvn:
              type: string
            institution:
              type: object
              properties:
                name:
                  type: string
                bank_code:
                  type: string
                type:
                  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
    Transaction:
      type: object
      properties:
        id:
          type: string
        narration:
          type: string
        amount:
          type: integer
        type:
          type: string
          enum: [debit, credit]
        balance:
          type: integer
        date:
          type: string
          format: date-time
        category:
          type: string
    TransactionList:
      type: object
      properties:
        status:
          type: string
        message:
          type: string
        data:
          type: array
          items:
            $ref: '#/components/schemas/Transaction'
        meta:
          type: object
          properties:
            total:
              type: integer
            page:
              type: integer
    Statement:
      type: object
      properties:
        status:
          type: string
        message:
          type: string
        data:
          type: object
          properties:
            account:
              type: object
            balance:
              type: integer
            transactions:
              type: array
              items:
                $ref: '#/components/schemas/Transaction'
    Identity:
      type: object
      properties:
        status:
          type: string
        message:
          type: string
        data:
          type: object
          properties:
            full_name:
              type: string
            email:
              type: string
            phone:
              type: string
            gender:
              type: string
            dob:
              type: string
            bvn:
              type: string
            marital_status:
              type: string
    Income:
      type: object
      properties:
        status:
          type: string
        message:
          type: string
        data:
          type: object
          properties:
            average_monthly_income:
              type: number
            estimated_salary:
              type: number
            yearly_income:
              type: number
            income_sources:
              type: array
              items:
                type: object
                properties:
                  employer:
                    type: string
                  amount:
                    type: number
                  frequency:
                    type: string
    InitiatePaymentRequest:
      type: object
      required:
        - amount
        - type
        - reference
      properties:
        amount:
          type: integer
          description: Amount in the lowest denomination (e.g. kobo).
        type:
          type: string
          example: onetime-debit
        method:
          type: string
          example: account
        description:
          type: string
        reference:
          type: string
        redirect_url:
          type: string
        customer:
          type: object
          properties:
            email:
              type: string
            phone:
              type: string
            address:
              type: string
            identity:
              type: object
              properties:
                type:
                  type: string
                number:
                  type: string
        meta:
          type: object
    InitiatePaymentResponse:
      type: object
      properties:
        status:
          type: string
        message:
          type: string
        data:
          type: object
          properties:
            id:
              type: string
            mono_url:
              type: string
            type:
              type: string
            reference:
              type: string
            customer:
              type: string
    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
    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
    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
    CustomerList:
      type: object
      properties:
        status:
          type: string
        message:
          type: string
        data:
          type: array
          items:
            $ref: '#/components/schemas/Customer'
    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
    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
    DebitMandateRequest:
      type: object
      required:
        - amount
        - reference
      properties:
        amount:
          type: integer
        reference:
          type: string
        narration:
          type: string
    StatusMessage:
      type: object
      properties:
        status:
          type: string
        message:
          type: string
    Error:
      type: object
      properties:
        status:
          type: string
        message:
          type: string