Senior Backend Developer (High Throughput APIs)

Quick Facts

• Role: Senior Backend Developer (High Throughput APIs)
• Sector: Payments / Fintech
• Focus: Scalable backend services and B2B APIs for high-volume financial processing

Description

Emagine is seeking a Senior Backend Developer to design and evolve core financial processing backend services and B2B APIs. You will own complex technical challenges end-to-end, ensuring high performance, scalability, reliability, and security. The work includes modernization of existing PHP and Java modules toward Go.

Responsibilities

• Design and develop highly scalable backend services and B2B APIs
• Build and maintain systems handling very high transaction volumes
• Design APIs, services, data models, and distributed systems for scalability and reliability
• Write clean, maintainable, testable, production-ready code
• Optimize relational database queries and indexing; troubleshoot SQL and database performance bottlenecks
• Implement asynchronous processing and support concurrent workloads
• Modernize and migrate legacy PHP and Java modules toward Go
• Design resilient systems with retry, recovery, and dead-letter mechanisms
• Implement observability with structured logging, metrics, tracing, and production monitoring
• Apply security principles across API and service design/implementation
• Contribute to automated testing, CI/CD, containerization, and production deployments
• Review code and provide meaningful feedback on designs

Requirements

• Strong proficiency in PHP and Java
• Experience designing and developing backend systems
• Strong understanding of relational databases and SQL optimization
• Experience with high-transaction-volume systems
• Familiarity with asynchronous processing and concurrent workloads
• Ability to contribute to system design, architecture, and security
• Strong problem-solving skills with focus on performance, scalability, and reliability
• Professional fluency in English
• French fluency is a plus

Benefits

• Work on a core financial processing platform with a collaborative engineering team
• Opportunity to grow while contributing to high-performance, scalable, and secure backend architecture