Backend API Developer Needed – Duplicate Transaction Handling

Filled
February 25, 2026
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Job Description

Type: Freelance / Contract / Remote

Project Overview

We are looking for an experienced Backend API developer to resolve critical issues related to duplicate transactions occurring during retry scenarios.

The project involves:

  • Analyzing the current API implementation
  • Identifying the root cause of duplicate transactions
  • Implementing robust, scalable solutions to prevent future occurrences
  • Ensuring proper error handling, logging, and idempotency in the system

This is a high-impact task where reliability, performance, and data integrity are critical.

Key Responsibilities

  • Review and audit existing backend API code for transaction processing
  • Identify flaws in transaction handling under retry or failure conditions
  • Implement idempotent API patterns to prevent duplicate transaction creation
  • Improve error handling, logging, and monitoring for transactional APIs
  • Test and validate changes to ensure robust operation under concurrent/retry conditions
  • Document changes and provide recommendations for long-term stability

Required Skills

  • Strong experience in backend API development (Node.js, Python, Java, Go, or similar)
  • Deep understanding of transaction management, concurrency, and retry mechanisms
  • Familiarity with database transactions (PostgreSQL, MySQL, or equivalent)
  • Experience implementing idempotent APIs
  • Strong problem-solving and debugging skills
  • Ability to deliver high-quality, production-ready code

Nice-to-Have

  • Experience with microservices and distributed systems
  • Knowledge of messaging queues (Kafka, RabbitMQ, SQS, etc.)
  • Experience with unit testing and automated testing of transactional flows