Back-End Engineer (Java/Spring Boot)

Nostro is seeking a skilled Back-End Engineer with professional experience in Java and Spring Boot to join their fully remote team based in Pakistan. This role involves building and maintaining critical back-end systems that manage users’ money, including USD accounts, debit cards, payment links, and peer-to-peer transfers. The ideal candidate will have hands-on experience designing APIs, data models, and services that prioritize correctness, reliability, and security. You will collaborate closely with product, design, and operations teams to deliver seamless financial infrastructure that empowers global earners.

Key Responsibilities
- Design and develop Spring Boot services and REST APIs for accounts, ledgers, cards, payment links, and P2P transfers.
- Ensure correctness, idempotency, and auditability are integral to all solutions.
- Model data effectively in PostgreSQL, writing safe and efficient queries, transactions, and migrations.
- Integrate with banking partners, card processors, and KYC/AML providers, managing webhooks, retries, and partial failures.
- Build reconciliation and monitoring systems to detect discrepancies proactively.
- Write clean, well-tested code and participate in thorough code reviews.
- Enhance performance, reliability, and security across all services.
- Troubleshoot and resolve production issues, including participating in an on-call rotation.
- Maintain technical documentation and contribute to improving CI/CD, deployment, and observability practices.

Required Qualifications
- Minimum of 1 year of professional experience developing production back-end services using Java and Spring Boot.
- Strong understanding of Spring fundamentals such as dependency injection, Spring Data JPA/Hibernate, @Transactional, Spring Security, and configuration profiles.
- Proficiency in PostgreSQL, including schema design, indexing, transactions, isolation levels, and locking mechanisms.
- Working knowledge of concurrency in Java, including thread safety and preventing race conditions and double-processing.
- Experience designing REST APIs with considerations for authentication, authorization, versioning, and webhooks.
- Skilled in testing frameworks like JUnit and Mockito; familiarity with Testcontainers is a plus.
- Knowledge of secure coding practices, including data protection, secrets management, and OWASP Top 10 vulnerabilities.
- Comfortable with Git workflows, including pull requests, code reviews, and branching strategies.
- Strong written and verbal communication skills in English, with the ability to work independently in a remote environment.
- Bachelor’s degree in Computer Science, Engineering, or equivalent practical experience.

Preferred Qualifications and Benefits
- Experience in fintech, particularly in payments, banking, wallets, lending, or similar domains involving money movement.
- Understanding of financial concepts such as idempotent operations, double-entry ledgers, reconciliation, and using BigDecimal for monetary values.
- Exposure to card issuing, payment links, or cross-border/multi-currency payments.
- Familiarity with regulatory and compliance standards such as PCI DSS, KYC/AML, and SBP regulations.
- Experience with database migration tools like Flyway or Liquibase.
- Knowledge of message queues or event-driven architectures (e.g., Kafka, RabbitMQ, SQS).
- Hands-on experience with AWS, Docker, and infrastructure as code.
- Previous work experience in an early-stage startup environment.

What Nostro Offers
- Competitive monthly salary ranging from PKR 150,000 to 225,000.
- Fully remote working arrangement.
- Opportunity to contribute to meaningful financial infrastructure that supports global earners.

Nostro is an equal opportunity employer and welcomes applicants from all backgrounds. Candidates are encouraged to apply by submitting a detailed CV highlighting their professional Java and Spring Boot experience, a brief description of a back-end system they have worked on (especially if it involved money), and a challenging problem they solved in that context.