Backend Developer, Payment Integration

Role Overview
We are hiring Backend Developers to build, optimize, and maintain high-throughput backend services for our client's payment solution. You will work on real-time transaction processing systems, custom ISO 8583 message parsing, secure credential management, and high-performance data storage (Redis, DynamoDB, SQL).
Key Responsibilities
Develop and optimize backend transaction routing engines and host interfaces for integration with Vietnamese domestic banks.
Implement custom handlers and data mappers for local bank variations of ISO 8583 messaging standards.
Design high-concurrency, low-latency data access layers using Redis (for session state/caching), DynamoDB (for audit logs/unstructured transaction context), and SQL (PostgreSQL/MySQL for relational ledger and transactional data).
Implement robust security mechanisms, token management, dynamic key exchange, and encrypted payload handling between merchant mobile apps and processor backends.
Assist host engineering teams in integrating the Host Library into target domestic bank switch environments.
Assist enterprise merchants troubleshooting SDK integrations, server-to-server callbacks, and webhook notifications.
Requirements & Qualifications
3+ years of backend engineering experience (Java, Go, [protected info], Python, or C#) within payment processing, banking, or high-volume transactional platforms.
Deep hands-on experience with Redis, DynamoDB, SQL.
Demonstrated knowledge of ISO 8583 protocols, socket communication, TLS security, and PIN block encryption standards.
Understanding of distributed systems, high availability, microservices architecture, and circuit-breaking patterns.
Prior experience supporting third-party SDKs, client app integrations, or working on local bank card switch projects.