Senior Software Engineer I (Full Stack)

At Halcyon Labs , we’re helping our customers make the world a safer place. Our All-Cause Fraud prevention platform combines AI, behavioral biometrics and consortium intelligence to stop fraud, not customers across the globe. We’re a team that makes things happen, stays humble, adapts fast, and keeps it real, growing our business and each other every day. As a Senior Software Engineer, you will be responsible for designing, developing, testing, and maintaining high-quality software applications that meet our business needs and align with industry best practices. You will have the opportunity to work on exciting and challenging projects that contribute to our company's growth and technological innovation. Our Senior Software Engineer will be responsible for driving technical decisions and must stay abreast of advancements in related technologies. Working with the broader R&D team, focusing on developing new features and supporting existing customers. You will bring the right engineering capabilities to the existing team to make it more cohesive and effective. Essential Duties Design, develop, test, and maintain robust backend and full-stack web applications Translate complex business requirements into scalable technical solutions Lead performance tuning efforts across application layers — JVM, database queries, indexing, and caching strategies Drive code quality through best practices including code reviews, unit testing, and CI/CD adoption Integrate and maintain messaging systems and asynchronous workflows Develop and evaluate proof-of-concepts using emerging tools and frameworks Collaborate proactively with Product Management, QA, Program Management, and Technical Support across global time zones Contribute to technical documentation, including design specs and user manuals Mentor junior engineers and act as a technical lead on assigned workstreams Desired Requirements / Hands-on Experience BE/BTech/MCA/Equivalent degree in Computer Science or a related technical field from an accredited university or college with 4 + years of relevant experience Core Engineering 4+ years of professional software engineering experience Strong, hands-on Java development — deep understanding of core Java, concurrency, memory management, and JVM performance tuning Spring Boot (primary framework — must be highly proficient) Spring Framework and Hibernate / JPA RESTful API design and development Strong experience writing unit, integration, and performance tests — including frameworks such as JUnit, Mockito, and performance testing tools (e.g. JMeter, Gatling) JavaScript & Frontend Strong experience with at least one modern JavaScript framework — React, Angular, or Vue.js Proficiency in TypeScript is strongly preferred Understanding of frontend performance optimisation and build tooling (Webpack, Vite, etc.) Databases & Performance Tuning In-depth experience with MS SQL Server — including complex queries, stored procedures, triggers, indexing strategies, and execution plan analysis Experience with NoSQL databases, preferably Apache Cassandra Proven ability to diagnose and resolve performance bottlenecks at both the application and database layer Strong understanding of RDBMS design principles and data modelling Messaging & Integration Hands-on experience with RabbitMQ and Spring AMQP Familiarity with event-driven architecture and asynchronous processing patterns DevOps & Infrastructure Experience with CI/CD pipelines (Jenkins or equivalent) Comfortable working in Linux environments Exposure to containerisation and orchestration: Docker, Kubernetes Familiarity with cloud platforms: Azure and/or AWS Source Control Proficient with Git / GitHub, including branching strategies and code review workflows Nice to Have Python scripting or automation experience Experience with SAFe / Agile at scale Familiarity with fraud detection, authentication, or fintech domain knowledge Knowledge of observability tools (e.g. Grafana, Prometheus, ELK stack) Desired Behaviors Adaptability: Demonstrates flexibility and openness to change. Actively seeks and adopts improved approaches and processes. Proactive Action: Takes initiative and is driven by results. Takes ownership of actions and outcomes, meeting commitments and striving for high performance. Effective Workload Management: Makes timely decisions, prioritizes tasks effectively, solves problems, monitors results, and takes corrective action when necessary. Technical Proficiency: Possesses a solid understanding of their role and responsibilities, demonstrating competence in performing tasks and utilizing relevant technical skills. Continuous Learning: Takes personal responsibility for learning and development. Recognizes personal strengths and areas for improvement, actively seeks feedback, and embraces opportunities to learn. Effective Communication: Demonstrates strong facilitation and written communication skills. Clearly articulates ideas and proposals, actively listens to colleagues' perspectives