Senior Backend Engineer - Checkout

Role Overview

Senior Backend Engineer - Checkout at Salla, focused on designing, building, and scaling highly available backend systems that power mission-critical payment experiences, checkout flows, promotions, loyalty, pricing, and financial services.

Role Purpose

Design, build, and operate scalable backend services supporting Fintech, Checkout, Promotions, Loyalty, and Payment systems. You will solve complex distributed systems problems, build high-performance services, and deliver resilient, observable, and maintainable systems that directly impact millions of transactions.

Key Responsibilities

System Design and Architecture

• Design and evolve RESTful APIs and integrations with internal platforms, payment gateways, and third-party services.
• Drive architectural decisions with scalability, resilience, maintainability, and operational excellence in mind.
• Participate in architecture discussions, technical design reviews, RFCs, and engineering planning.

Development and Code Quality

• Develop clean, maintainable, and high-performance production code with readability and long-term ownership in mind.
• Build reliable distributed systems capable of handling high traffic, failures, and asynchronous workloads.
• Write comprehensive unit and integration tests while maintaining high engineering standards through code reviews.
• Leverage AI-assisted engineering tools responsibly to accelerate development, debugging, testing, documentation, and code quality.

Performance and Optimization

• Optimize application performance across services, databases, caching layers, queues, and background workers.

Operations and Reliability

• Ensure services are production-ready through monitoring, logging, alerting, testing, and observability best practices.
• Contribute throughout the full software development lifecycle, from design through deployment and production support.
• Continuously improve system reliability, developer experience, and engineering standards across the team.

Mentorship and Leadership

• Mentor junior and mid-level engineers through technical leadership, design discussions, and engineering best practices.

Qualifications & Experience

• 6+ years of professional software engineering experience building production backend systems.
• Strong experience building scalable backend services in at least one modern language such as PHP, Go, Java, or C#.
• Experience with PHP and Laravel is preferred but not required.
• Strong understanding of distributed systems fundamentals, including consistency, availability, concurrency, fault tolerance, idempotency, asynchronous processing, messaging, and caching.
• Experience designing and operating high-scale, highly available backend systems.
• Proven ability to write clean, maintainable, efficient, and high-performance production code.
• Strong understanding of software engineering principles, including SOLID, design patterns, clean architecture, and domain-driven design concepts.
• Experience designing RESTful APIs and integrating with third-party platforms and payment providers.
• Strong SQL knowledge with experience designing and optimizing MySQL or PostgreSQL databases.
• Experience with caching technologies, queues, background workers, and performance optimization.
• Experience writing automated tests, participating in code reviews, and working within modern CI/CD pipelines.
• Comfortable using AI-assisted development tools to improve productivity, software design, implementation, testing, debugging, documentation, and code reviews.

Skills & Competencies

• Backend development in PHP, Go, Java, or C#.
• Distributed systems design and operation.
• RESTful API design and integration.
• MySQL or PostgreSQL database design and optimization.
• Caching technologies, message queues, and background job processing.
• Automated testing and code review practices.
• CI/CD pipeline integration.
• AI-assisted development tools.
• SOLID principles and design patterns.
• Clean architecture and domain-driven design.

Additional Information

Preferred Qualifications

• Experience building Fintech, Payments, Checkout, Loyalty, Pricing, Promotions, or other high-volume transactional systems.
• Experience with event-driven architectures and distributed messaging systems.
• Experience with Docker, Kubernetes, cloud platforms (AWS, GCP, or Azure), and Infrastructure as Code.
• Experience with observability platforms, distributed tracing, metrics, and production monitoring.
• Experience working within microservices or service-oriented architectures.
• Bachelor's or Master's degree in Computer Science, Software Engineering, or a related field.