Offramp Flow (Sell Crypto)

• Rate locking (60 seconds validity)
• Two flow modes: External wallet or Integrated wallet
• Automatic refunds on fiat transfer failure
• Multi-network crypto support (EVM, TRON, Lightning, Stellar)

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1. Transaction Initiation & Rate Locking

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2. Crypto Receipt

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External Wallet Flow

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Integrated Wallet Flow

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3. Fiat Disbursement

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Mobile Money Disbursement

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Bank Transfer Disbursement

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4. Automatic Refund (On Fiat Failure)

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5. Webhook Notification

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Transaction Statuses

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Crypto Networks Supported

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EVM Chains

• Networks: Ethereum, Polygon, Arbitrum, Base, Optimism, Celo
• Tokens: USDT, USDC, DAI
• Confirmations: 3 blocks required

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TRON

• Tokens: USDT (TRC20)
• Confirmations: Verified via TronGrid

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Lightning Network

• Use Case: Fast Bitcoin offramps
• Payment: Lightning invoice

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Stellar

• Tokens: USDC, other Stellar assets
• Confirmations: Near-instant

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Key Features

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Rate Locking

• Exchange rate locked at transaction creation
• Valid for 60 seconds
• Must request new rate if expired

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Automatic Refunds

• Triggered 5 minutes after fiat transfer failure
• Up to 3 retry attempts
• Returns crypto to original sender address
• Track via /offramp/refund-status/:referenceId

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Flexible Wallet Options

• External Wallet: User controls private keys
• Integrated Wallet: Platform-managed for instant processing

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Error Handling

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Rate Expired

{
  "statusCode": 400,
  "message": "Rate expired. Rates are valid for 60 seconds."
}

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Insufficient Crypto Amount

{
  "statusCode": 400,
  "message": "Insufficient crypto amount"
}

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Fiat Transfer Failed (Auto-Refund)

{
  "status": "REFUND_PENDING",
  "message": "Fiat transfer failed. Crypto refund will be processed in 5 minutes.",
  "refund": {
    "cryptoAmount": 10.5,
    "currency": "USDT",
    "network": "Polygon"
  }
}

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Best Practices

• Pre-Check Rates: Use /rates/offramp-rate before creating transaction
• Validate Addresses: Ensure sender address format matches network
• Handle Callbacks: Implement webhook endpoint with HMAC verification
• Monitor Refunds: Check refund status via /offramp/refund-status/:referenceId
• Bank Transfers: Verify bank account details before submission

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Testing

• Crypto amounts ending in .00 trigger success
• Crypto amounts ending in .99 trigger fiat failure + refund
• Crypto amounts ending in .88 trigger timeout