Senior Backend Software Engineer – PHP

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 professi