Maksudur Rahman
Maksudur Rahman
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Case Study2023 - Present

Payment Gateway Integration

A transaction-heavy backend service built to route payments directly to local banking systems, featuring transaction checks, webhook sequencing, and automated reconciliation.

Role

Lead Developer

Sector

Fintech

terminal://payment-gateway-redis
HMAC Signature VerifiedLatency: 184ms

The Challenge

  • Lock contention and double-payment bugs under highly concurrent callbacks.
  • Varying and inconsistent response formats from different bank endpoints.
  • Out-of-order webhook delivery causing transaction state corruption.

Our Solution

  • Implemented distributed locking using Redis to block duplicate callbacks.
  • Built a normalized adapter layer to standardize all incoming API payloads.
  • Designed a database transaction logging queue to enforce state transitions.

Measured Impact

"Successfully handled payment callbacks for thousands of daily checkouts with zero duplicate payments and an average routing latency under 200ms."

System Reliability Verified