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.

Requirements

- 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.

Benefits

- Competitive Compensation - Competitive salary package.
- Career Growth - Career development opportunities in a growing integral 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.

📌 Mid-Senior Java Software Engineer (Remote - Argentina)-DV (Buenos Aires)
🏢 OKTO PAYMENTS
📍 Buenos Aires