Payment Microservices Tech Lead (Java) | Contract (Lithuania Only)

We are looking for an experienced Payment Microservices Tech Lead to provide technical leadership, support solution design, and guide the development of modern payment and transaction platforms. The role involves hands-on development and architecture governance across Java 21 , Spring Boot 3.x , microservices architecture , REST APIs , messaging platforms, AWS , and secure integration solutions. The project focuses on payment microservices covering SWIFT , VISA card payments , and SEPA payments . Key Responsibilities: Provide technical leadership across the engineering team. Review and approve code , requirements documentation, and integration documentation. Prepare Solution Design documents and contribute as a hands-on development team member. Design and develop microservices using Java 21 and Spring Boot 3.x. Implement and maintain REST API integrations and asynchronous messaging with Kafka or RabbitMQ. Manage database interactions with SQL , MS SQL , and/or MySQL. Deploy and operate services on AWS , including ECS , VPC , and CloudWatch. Implement and maintain OAuth2 and JWT authentication and authorization flows. Maintain and improve CI/CD pipelines using Bitbucket Pipelines. Must-Have Requirements: Expert-level hands-on experience with Java 21 and Spring Boot 3.x. Proven experience designing and building a microservices architecture. Strong proficiency in REST API design principles. Hands-on experience with Kafka or RabbitMQ. Solid knowledge of SQL databases, specifically MS SQL and/or MySQL. Working experience with AWS services such as ECS , VPC , and CloudWatch. Practical knowledge of OAuth2 and JWT security standards. Experience with CI/CD pipelines, particularly Bitbucket Pipelines. Demonstrated ability to lead technical teams and conduct code and design reviews. Nice to Have: Experience with SWIFT payments integration. Familiarity with PCI DSS and/or PSD2 compliance frameworks. Hands-on implementation experience with 3DS2 authentication flows. Background working with high-load transactional systems. Experience with event-driven architecture patterns.