Principal Software Engineer

Powering the world’s payments ecosystem

ACI powers the payments ecosystem – globally, and you power ACI. You’ll innovate, collaborate, and grow – in an energetic technology culture with decades of proven success. ACIers – in all roles and levels – are truly your colleagues and many are your friends. Our size and reach allow you to see the global impact of your work. You are visible, your talents are valued, and you are empowered to shape the future of payments.

As a Principal Software Engineer in Timisoara, Romania you will join a diverse, passionate team, dedicated to powering the world’s payments ecosystem!

This role will be part of the PRM product, a Fraud Detection engine, based on neural networks and database rules. It is used by banks and financial institutions to identify financial transactions sent by fraudsters instead of legitimate cardholders, based on configurable rules and spending patterns. It is designed for maximum performance and availability, being able to process thousands of online transactions per second. 

We are looking for a Principal Software Engineer to lead the design and development of high‑performance, scalable software systems used in mission‑critical environments. This role requires deep expertise in Java backend development, and strong software design skills. ML engineering and/ or DevOps knowledge is considered a strong plus. 

If you are interested in helping people protect their money from fraudsters and passionate about building high-performance complex systems, come and join us! 

The purpose of the Principal Software Engineer is:

Leads the architecture, design and development of software solutions across backend and frontend components. Acts as a technical authority within the engineering organization, driving best practices, code quality and long‑term system evolution. 

A typical day at ACI for a Principal Software Engineer is:

• Independently designs, develops, tests, delivers and maintains high‑quality software solutions with minimal supervision. 
• Provides technical leadership across Java backend and Angular frontend development, ensuring clean architecture and consistent design patterns. 
• Leads the breakdown and implementation of complex features, coordinating design and task execution across teams. 
• Creates, reviews and maintains technical deliverables such as: Architecture and design documents, Technical specifications, Code and API documentation, Installation and operational guides, best‑practice guides. 
• Influences and contributes to technical direction and standards for products and projects. 
• Acts as a subject matter expert, providing guidance, mentoring and code reviews across the development organization. 
• Ensures non‑functional requirements are met, including performance, scalability, security, availability and maintainability. 
• Isolates and resolves complex, cross‑system issues spanning code, infrastructure, networking and cloud platforms. 
• Collaborates with DevOps, QA and platform teams to improve build, deployment and operational readiness. 
• Uses DevOps knowledge (where applicable) to promote automation, CI/CD best practices and operational awareness. 
• Drives continuous improvement in software engineering practices, tools and processes. 
• Drives automation-first approaches to provisioning, deployment, testing and operational tasks to reduce risk and manual effort. 
• Anticipates customer and operational needs, proposing solutions that improve system reliability, deployment confidence and time‑to‑market. 
• Ensures security and compliance requirements are embedded into pipelines and environments. 
• Stays up to date with emerging technologies. 
• Understands and adheres to all corporate policies, including the ACI Code of Business Conduct and Ethics. 
• Performs other duties as assigned. 

Knowledge, Skills and Experience and Experience needed to succeed in this role:

• Bachelor’s degree in Computer Science or related field or equivalent professional experience. 
• 15+ years of professional software development experience, with a strong focus on enterprise systems 
• Strong understanding of modern software architecture and non‑functional requirements (availability, scalability, performance, security, reliability). 
• Strong expertise in Java and modern backend development frameworks. 
• Proven experience with Angular and building user‑facing applications. 
• Solid understanding of object‑oriented design, clean architecture and software design patterns. 
• Strong experience implementing and validating non‑functional requirements (performance, scalability, security, availability). 
• Ability to design and coordinate implementation for complex technical solutions. 
• Experience with Git / GitHub or similar version control systems. 
• Experience working with relational databases (e.g. Oracle, MS SQL) and understanding production data considerations. 
• Proven experience designing and operating CI/CD pipelines using Git‑based workflows (Git / GitHub). 
• Experience with cloud platforms, preferably Microsoft Azure. 
• Familiarity with ethical AI principles, data privacy considerations, and responsible use of AI in enterprise systems. 
• Exposure to AI‑assisted developer tools (e.g. coding assistants, automated testing or code analysis tools) and an interest in leveraging AI to improve engineering productivity. 
• Knowledge of Agile / Scrum development practices. 
• Ability to break down complex systems and coordinate design and execution across multiple teams. 
• Experience working in multi‑cultural, geographically distributed teams. 
• Strong communication, mentoring and stakeholder‑management skills. 
• Nice to have: Hands‑on experience with containers and orchestration platforms (Docker, Kubernetes); Experience with Infrastructure as Code (e.g. Terraform); Experience collaborating across disciplines (engineering, data science, product) to translate AI capabilities into production‑ready software solutions; Experience building or enhancing Java‑based applications that leverage AI outputs as part of core business workflows 

Core Capabilities:

We seek colleagues who embody our core capabilities — these shape our culture and enable us to make a meaningful impact together:

• Ensure Accountability: holding self and others accountable to meet commitments.

• Drives Results: consistently achieving results, even under tough circumstances.

• Customer Focus: building strong customer relationships and delivering customer-centric solutions.

• Cultivate Innovation: creating new and better ways for the organization to be successful.

• Collaborates: building partnerships and working collaboratively with others.

• Courage: stepping up to address difficult issues, saying what needs to be said.

Applicants must be currently authorized to work in Romania on a full-time basis. This position does not offer sponsorship for employment visa status or work permit now or in the future.

In return for your expertise, we offer opportunities for growth, career development, and a competitive compensation and benefits package—all within an innovative and collaborative work environment.

Are you ready to help us transform the payments ecosystem? To learn more about ACI Worldwide, visit our web site at www.aciworldwide.com

ACI Worldwide is an AA/EEO employer in the United States, which includes providing equal opportunity for protected veterans and individuals with disabilities, and an EEO employer globally.

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