Principal Software Engineer (.NET)

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 (.NET) in Pune, you will join a diverse, passionate team, dedicated to powering the world’s payments ecosystem!

Job Summary

ACI Worldwide is seeking a Principal Software Engineer to provide technical leadership and architectural direction for mission-critical payment solutions.

This role requires deep expertise in .NET, C#, Microservices, Cloud Technologies, Distributed Systems, DevOps practices , QA automation practices and AI-enabled solutions, with a proven ability to influence engineering strategy and drive innovation across multiple teams.

Key Responsibilities

• Define architecture, technical strategy, and engineering standards for enterprise-scale applications.
• Design and deliver scalable, secure, and high-performance solutions using modern .NET technologies.
• Lead cloud-native and microservices-based transformation initiatives.
• Drive engineering excellence through architecture reviews, technical mentorship, and best practices.
• Partner with Product, Engineering, and Business leaders to align technology investments with business goals.
• Evaluate and adopt emerging technologies, including AI and intelligent automation.

Required Qualifications

• Bachelor's degree in Computer Science or related field.
• 12+ years of software engineering experience with demonstrated technical leadership.
• Proven track record designing and delivering large-scale enterprise software solutions.
• Experience leading architecture and technical initiatives across multiple teams.
• Payments, FinTech, Banking, or other regulated industry experience preferred.

Technical Expertise

• Expert proficiency in C#, .NET Core/.NET 8+, Angular 15+ , ASP.NET Core, Entity Framework, Ngnix and REST & SOAP APIs.
• Deep expertise in Microservices, Distributed Systems, Event-Driven Architecture, and Domain-Driven Design.
• Strong experience with AWS(preferred),Azure , Docker, Kubernetes, and CI/CD pipelines.
• Infrastructure understanding – E2E request flow , Load-balancer , Akamai , firewalls , SAML
• QA automation Practices and tools usages – like Selenium , playwright , AI based tools
• Experience with RabbitMQ, MSMQ , SQL Server.
• Strong understanding of performance optimization, scalability, resiliency, and application security.

AI & Emerging Technologies

• Experience integrating Generative AI, AI/ML, LLMs, RAG, or AI-powered capabilities into enterprise applications.
• Knowledge of AI development tools and modern software engineering productivity platforms.
• Ability to identify and drive AI initiatives that improve customer experience, operational efficiency, and product innovation.

Professional Skills

• Excellent communication and stakeholder management skills.
• Strong architectural mindset with a focus on business outcomes.
• Ability to influence and lead without direct authority.
• Passion for mentoring and developing engineering talent.

Preferred Qualifications

• Experience building enterprise payment or financial technology platforms.
• Cloud and architecture certifications.
• Experience leading large-scale modernization, cloud, or AI transformation programs.
• Industry thought leadership, publications, patents, or conference speaking experience.

Ideal Candidate

A hands-on Principal Engineer with expertise in .NET, Cloud, Microservices, Distributed Systems, and AI technologies, capable of shaping technical strategy while delivering highly scalable, secure, and mission-critical enterprise solutions.

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.

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

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