Senior Java Developer – Acquiring Transactional Switch / Authorizer

Description

Job Summary: We are seeking a Senior Java Developer with solid experience in Switch / Acquiring Transactional Authorizer to work in a dynamic, high-criticality environment. Key Highlights: 1. Working with robust payment systems 2. Contributing to performance, security, and scalability 3. Impacting thousands of transactions daily We are looking for a Senior Java Developer with solid experience in Switch / Acquiring Transactional Authorizer to work in a dynamic, high-criticality environment handling large transaction volumes. This is an opportunity for professionals who wish to work with robust systems directly tied to the payment ecosystem, contributing to the performance, security, and scalability of mission-critical business solutions. If you possess strong analytical skills, enjoy tackling complex technical challenges, and want to work on projects impacting thousands of transactions daily, this position could be your next career step. **Requirements:** **Proven experience with:** Backend / Core Java Core (JDK 21\+); Development of high-performance, low-latency applications; Concurrent programming (multithreading, parallelism); Distributed and scalable systems; Concurrency control, idempotency, and parallel processing; Development of resilient, fault-tolerant systems; Cloud \& Infrastructure Cloud Computing (OpenShift, AWS, Azure, GCP); Containers (Docker, DockerHub); Using Redis as a distributed cache for high-transaction performance; Experience with messaging systems (Kafka, RabbitMQ); Databases RDBMS (SQL Server, Oracle or similar); NoSQL (Cassandra or others); Modeling for high-volume transactional workloads; Payment Systems (ESSENTIAL) Strong knowledge of card authorization systems; Experience with ISO8583 protocol (Visa, Mastercard, Elo, Amex), including message parsing, assembly, and troubleshooting; **Integration with networks for:** Acquisition; Authorization; Risk systems; Card brands; Experience with ISO8583 messaging simulators; Security Applied cryptography for payment systems; Integration with HSM; Tools Git; Jira or equivalent tools; Java IDEs (IntelliJ, Eclipse); Language Technical English for reading documentation (Visa, Mastercard, etc.); Desirables (Nice-to-have) Experience with C/C\+\+; Spring Boot and Spring Batch; Experience with observability (logs, tracing, metrics); Knowledge of high-availability (HA) system architecture; **Experience with AI applied to development (e.g.:** using tools like Claude or similar);