Mid-Senior Java Software Engineer (Remote - Argentina) - ARG112-DV

OKTO’s continuous growth demands high-caliber candidates who embody professionalism, passion, and creativity. For those who join us, we offer significant career advancement, stimulating challenges, and a clear runway for growth. OKTO is the next-generation Payment Service Provider — AI-native, precision-engineered, and relentlessly merchant-obsessed.

Built for merchants operating in the most complex and demanding eCommerce sectors, our platform goes far beyond transaction processing. We solve for scale, compliance, and performance with one unshakable focus: delivering outcomes that power merchant growth. From payments and banking to treasury and settlement, we engineer the financial infrastructure that gives our partners a competitive edge.

The result? Faster onboarding, smarter operations, and resilient, real-time performance. At OKTO, we enable merchants to Play Differently, transforming payments from routine transactions into true differentiators that deliver personalized, frictionless experiences.

Our AI-native innovation harnesses data and insight to power every decision, while our proprietary in-house engineering ensures precision and control. Combined with deep, trust-based relationships worldwide, we’re redefining what it means to build, scale, and win in complex digital commerce.

Summary As a Java Middleware Engineer , you will play a key role in designing, developing, and maintaining the middleware services that power our next-generation payment platform. You will contribute to the development of scalable, secure, and high-performance applications that process millions of financial transactions, while collaborating with Product, Architecture, Infrastructure, QA, and Security teams.

Key Responsibilities Design, develop, and maintain middleware applications and backend services using Java and Spring technologies. Develop new product features and platform capabilities based on business and technical requirements. Build scalable, resilient, and high-performance microservices that support payment processing and financial transaction workflows.

Write clean, maintainable, and performance-optimized code, ensuring high-quality standards and comprehensive unit test coverage. Participate in the design and implementation of distributed systems and event-driven architectures. Develop and maintain RESTful APIs and secure service integrations using modern authentication mechanisms such as OAuth2.

Support System Integration Testing (SIT), User Acceptance Testing (UAT), and Production environments, identifying and resolving issues to ensure platform stability. Collaborate with cross-functional teams, including Product Managers, QA Engineers, DevOps Engineers, and Solution Architects, to deliver high-quality software solutions.

Participate in Agile ceremonies, code reviews, technical discussions, and knowledge-sharing initiatives. Contribute to continuous improvement by identifying opportunities to optimize software quality, development processes, and system performance. Work with version control systems and CI/CD pipelines, following engineering best practices and software development standards.

Produce technical documentation, including product specifications, design documentation, and implementation details. Bachelor's degree in Computer Science, Computer Engineering, Software Engineering, Information Technology, or a related field. Minimum of 5 years of professional experience developing middleware or backend applications using Java.

At least 1 year of hands-on experience with Java 11 or newer . Proven experience working within the FinTech, Payments, Banking, or Financial Services industry. Strong understanding of Object-Oriented Design (OOD), SOLID principles, and Functional Programming concepts.

Experience designing and developing microservices architectures using Spring Boot and Spring Cloud (Netflix OSS) . Solid knowledge of the Spring Framework 5 ecosystem. Experience implementing secure authentication and authorization using OAuth2 .

Experience with JPA , ORM modeling, and persistence frameworks. Strong experience designing and developing RESTful APIs. Familiarity with Event-Driven Architecture, asynchronous messaging, and distributed software design patterns.

Experience working with Git and collaborative source control workflows. Good understanding of software development best practices, including unit testing, clean code principles, and code review processes. Strong analytical, problem-solving, and troubleshooting skills.

Ability to work independently while collaborating effectively within an international engineering team. Excellent technical writing skills for documenting requirements, software designs, and technical specifications. Preferred Qualifications Experience with cloud platforms such as AWS.

Familiarity with CI/CD pipelines and DevOps practices. Experience working in high-volume transaction processing environments. Knowledge of payment processing concepts, transaction lifecycle, settlement, reconciliation, or payment gateway integrations.

Experience with monitoring, logging, and application performance optimization. Languages Advanced English (mandatory), with the ability to participate in technical discussions, collaborate with international teams, and produce technical documentation. Spanish (mandatory).

Please submit your resumé in English. Competitive Compensation - Competitive salary package. Career Growth - Career development opportunities in a growing global fintech.

Continuous Learning - Access to challenging projects and continuous learning opportunities. Inclusive Environment - Collaborative, diverse, and international work environment. Birthday Leave - Paid day off on your birthday.