# Best practice integration (Online shop)

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⏱ 3 min
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👤 Merchant Onboarding Team (Marcel K.)
## 1. Frontend

### Product page

#### Open Invoice

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Do’s ✔️
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Show the due date.
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Highlight that payments can be done after delivery.
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Don’ts ❌
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          Don’t show any Ratepay logo or state Ratepay as payment provider —
          stay within your brand.
        
#### Pay in 3

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Do’s ✔️
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Show the monthly amount.
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Don’ts ❌
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          Don’t show any Ratepay logo or state Ratepay as payment provider —
          stay within your brand.
        
### Checkout

#### Address page

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Do’s ✔️
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Implement an address validation service to improve acceptance quota.
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        Show the hint that the billing address needs to match with the registered
        address (Meldeadresse) for Ratepay payment methods.
      
#### Payment selection page

Payment selection page example
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Do’s ✔️
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General
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Evaluate which payment methods can be shown, based on basket amount.
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        Execute
        
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          Device Fingerprinting
        

        when a Ratepay payment method was selected.
      
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Ask & validate Date of Birth and/or telephone number (if not done before).
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        Show
        
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          legal requirements
        
.
      
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Direct Debit
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        Ask & validate Bank Account Owner & IBAN 
&
 get
        
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          SEPA mandate
        
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Pay in 3
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        Show
        
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          installment calculator with conditions
        
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Don’ts ❌
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General
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        Don’t show any Ratepay logo or state Ratepay as payment provider —
        stay within your brand.
      
## 2. Backend

### Payment processing

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Do’s ✔️
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        Implement
        
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          Idempotency
        

        for follow-up operations.
      
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        Forward Ratepay transaction details (e.g.
        
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          payment references
        
)
        to your ERP system.
      
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        Consider
        
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          transaction expiration date.
        
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Don’ts ❌
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Call Ratepay APIs from frontend.
### Invoicing

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Do’s ✔️
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Open Invoice
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State the bank details & 
a
legal requirements
, provided by Ratepay.
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        Forward the transaction specific
        
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          payment_references
        

        to your ERP system / system for invoice generation and state it on your invoices.
      
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Direct Debit
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        State, that the SEPA prenotification will be sent separately.
      
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Pay in 3
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        State, that the installment plan will be sent separately.
      
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Don’ts ❌
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General
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        Show your bank details on the invoices, to avoid a money transfer to you instead of Ratepay.
      
## 3. Frontend

### Show success / failure

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Do’s for success ✔️
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Show success page 
&
 send confirmation to buyer.
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Don’ts for failure ❌
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Show a generic error reason.
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        Still show Ratepay payment methods in case of hard risk rejections.
      
### Optional: Status in customer account

See [Transaction Status API](/docs/developer/transaction_status/payment_api_2_0/operations/other/gettransactionstatus)

Account overview example