Senior Backend Software Engineer – PHP & Java | High-Performance Systems

emagine; Portugal; Remote; EUR 70,000 - 110,000; Full time

Benefits offered by this job

100% remote (Portugal-based)

Opportunity to work on a mission‑crit

Job summary

emagine is seeking a highly experienced Senior Backend Engineer based in Portugal to join an international team and help design scalable, high‑volume financial backend systems using PHP and Java. You will own complex technical challenges, modernize services toward Go, optimize PostgreSQL queries, and ensure reliability, security, and performance across mission‑critical platforms in a fully remote setup.

This role emphasizes code quality, automated testing, CI/CD, and strong collaboration across

Qualifications

• Strong professional experience with both PHP and Java.
• Experience designing and developing scalable, high-performance backend services and REST APIs.
• Deep understanding of relational databases, SQL optimization, indexing, and query performance (PostgreSQL).
• Proven experience working with high-throughput, transaction-intensive, or business-critical systems.
• Strong knowledge of distributed systems, asynchronous processing, concurrency, and fault-tolerant architectures.
• Solid understanding of software architecture, system design, design patterns, and API security.
• Demonstrated ability to troubleshoot complex production issues and resolve performance bottlenecks.
• Strong commitment to code quality, automated testing, maintainability, and engineering best practices.
• Ability to work independently, take technical ownership, and make sound architectural decisions.
• Excellent analytical, troubleshooting, and problem-solving skills.
• Strong communication skills and the ability to collaborate effectively in an international engineering environment.
• Must currently reside in Portugal.

Responsibilities

• Design, develop, and maintain scalable backend services and B2B APIs using PHP and Java.
• Build robust, high-performance systems capable of processing large transaction volumes.
• Take end-to-end ownership of complex engineering challenges, from technical design to production.
• Design scalable APIs, data models, and distributed architectures with a strong focus on reliability, security, and maintainability.
• Contribute to the modernization and migration of existing PHP and Java services toward Go.

Skills

PHP

Java

REST APIs

Distributed systems

SQL optimization

Tools

PostgreSQL

Go

AWS

Job description

100% Remote | Must be based in Portugal

Are you a highly experienced Senior Backend Software Engineer who thrives on solving complex engineering challenges, designing scalable architectures, and building mission-critical systems?

We're looking for an exceptional Senior Backend Engineer to join an international engineering team responsible for developing and evolving a core financial processing platform handling high transaction volumes.

This is an opportunity for a technically strong professional with deep expertise in PHP, Java, backend architecture, distributed systems, and database performance, who is passionate about engineering excellence, scalability, and reliability.

You’ll play a key role in modernizing existing services, optimizing critical systems, and contributing to the evolution of the platform toward Go-based architectures.

What You’ll Be Doing:

• Design, develop, and maintain highly scalable backend services and B2B APIs using PHP and Java.
• Build robust, high-performance systems capable of processing large transaction volumes.
• Take end-to-end ownership of complex engineering challenges, from technical design to production.
• Design scalable APIs, data models, and distributed architectures with a strong focus on reliability, security, and maintainability.
• Contribute to the modernization and migration of existing PHP and Java services toward Go.

Performance, Scalability & Reliability:

• Identify and resolve performance bottlenecks across applications, databases, and distributed systems.
• Optimize PostgreSQL databases, including complex SQL queries, indexing strategies, and database performance.
• Design and implement asynchronous processing, concurrent workloads, and resilient architectures.
• Implement robust error-handling, retry, recovery, and dead-letter mechanisms.
• Ensure high availability, fault tolerance, and operational stability of business-critical services.

Engineering Excellence & DevOps:

• Develop clean, maintainable, well-tested, and production-ready code.
• Implement observability solutions using structured logging, metrics, distributed tracing, and monitoring tools.
• Apply security best practices throughout the software development lifecycle.
• Contribute to automated testing, CI/CD pipelines, containerization, and cloud deployments.
• Participate in code reviews, architecture discussions, and technical decision-making.
• Collaborate with experienced engineers to continuously improve engineering standards and practices.

What We’re Looking For – Must Have:

We’re looking for a genuinely senior engineer with outstanding technical depth, strong problem-solving abilities, and proven experience building complex backend systems.

• Strong professional experience with both PHP and Java, including hands-on development of production-grade backend applications.
• Extensive experience designing and developing scalable, high-performance backend services and REST APIs.
• Deep understanding of relational databases, SQL optimization, indexing, and query performance, ideally with PostgreSQL.
• Proven experience working with high-throughput, transaction-intensive, or business-critical systems.
• Strong knowledge of distributed systems, asynchronous processing, concurrency, and fault-tolerant architectures.
• Solid understanding of software architecture, system design, design patterns, and API security.
• Demonstrated ability to troubleshoot complex production issues and resolve performance bottlenecks.
• Strong commitment to code quality, automated testing, maintainability, and engineering best practices.
• Ability to work independently, take technical ownership, and make sound architectural decisions.
• Excellent analytical, troubleshooting, and problem‑solving skills.
• Strong communication skills and the ability to collaborate effectively in an international engineering environment.
• Must currently reside in Portugal.

Nice to Have:

• Hands-on experience with Go (Golang), particularly in backend services or system modernization.
• Experience migrating legacy applications or services to modern architectures.
• Experience with AWS and cloud-native environments.
• Familiarity with Grafana, Loki, Alloy, or similar observability and monitoring solutions.
• Experience with GitHub, CI/CD pipelines, Docker, and containerized environments.
• Previous experience in FinTech, banking, payments, or other high-volume transactional platforms.
• Experience working in Agile development environments.

What Makes This Opportunity Special?

• 100% remote opportunity, exclusively for professionals based in Portugal.
• Work on a mission-critical financial platform where performance, scalability, and reliability truly matter.
• Tackle challenging engineering problems involving high transaction volumes and distributed systems.
• Contribute to a strategic technology modernization journey involving PHP, Java, and Go.
• Collaborate with an experienced international engineering team.
• Have a meaningful impact on technical architecture, engineering decisions, and platform evolution.

Ready for Your Next Challenge?

If you’re a highly skilled Senior Backend Engineer with strong expertise in PHP and Java, a passion for complex technical challenges, and experience building scalable, reliable systems, we’d love to hear from you!