Java Software Engineer Jobs in O Fallon, MO (NOW HIRING)

Our Purpose

Mastercard powers economies and empowers people in 200+ countries and territories worldwide. Together with our customers, we're helping build asustainableeconomy where everyone can prosper. We support a wide range of digital payments choices, making transactionssecure, simple, smart and accessible. Our technology and innovation, partnerships and networks combine to deliver a unique set of products and services that help people, businesses and governments realize their greatest potential.

Title and Summary

Senior Software EngineerWho is Mastercard?
Mastercard is a global technology company in the payments industry, committed to powering an inclusive digital economy that benefits everyone, everywhere. By making transactions safe, simple, smart, and accessible, Mastercard enables individuals, financial institutions, governments, and businesses to achieve their full potential.
Through secure data, advanced networks, strong partnerships, and a culture rooted in innovation and purpose, Mastercard delivers solutions that create lasting impact. Guided by our Decency Quotient (DQ), we foster a culture of integrity, inclusion, and responsibility in everything we do. With operations spanning more than 210 countries and territories, we are building a sustainable world that unlocks priceless possibilities for all.
Overview
The Mastercard B&MI Technology Development team is seeking a Senior Software Engineer to drive innovation and enhance customer experience through scalable, high-impact technology solutions. Our team focuses on leveraging cutting-edge technologies to deliver advanced analytics and reporting capabilities to a diverse global customer base.
In this role, you will collaborate closely with product partners and cross-functional engineering teams to enhance existing platforms, design scalable solutions, and contribute to the development of new products that deliver meaningful customer value.
We are looking for a Senior AI Java Engineer (Hands-on IC) to deliver AI-driven capabilities across our roadmap. This is a builder role requiring strong hands-on engineering-owning critical components end-to-end and delivering production-grade, AI-enabled services with high standards of operability, security, scalability, and resilience.
This role blends Software Engineering (deterministic systems and reliable services) with AI Engineering (model lifecycle, monitoring, and continuous improvement of probabilistic systems).
Role (Essential Responsibilities)
In this role, you will:
Build and own Java services and APIs that deliver AI-powered features, ensuring performance, scalability, and maintainability in a distributed environment
Develop and productionize AI components in Python, supporting model training, tuning, and inference workflows
Implement and operate AI systems in production, including deployment frameworks, automated pipelines, and model lifecycle management (versioning, monitoring, and updates)
Own delivery across the full lifecycle-design, development, testing, deployment, configuration, and documentation-with a strong focus on automation and operational excellence
Design and develop secure, scalable, and reliable systems supporting global, customer-facing platforms
Drive engineering excellence through code reviews, testing discipline, and best practices, making pragmatic design and architectural decisions
Troubleshoot complex issues across distributed services and AI components, applying strong root-cause analysis and problem-solving skills
Mentor engineers through hands-on technical guidance and reviews, raising the bar on quality, scalability, and AI readiness
All About You
Must-Have Skills
The ideal candidate demonstrates strong, hands-on expertise across the following areas:
Strict Must-Haves (Non-Negotiable)
Python - Proven experience building and operationalizing production-grade AI components (code, testing, packaging)
AI Frameworks - Hands-on experience with modern AI frameworks (e.g., PyTorch, TensorFlow, Hugging Face) for model development, tuning, or serving
Core Engineering Skills
Strong Java engineering expertise, including designing, developing, testing, and maintaining scalable, high-performance systems
Proven ability to deliver reliable, production-grade software with strong testing discipline (unit, integration, and beyond)
Hands-on experience with the AI/ML lifecycle, including deployment, workflow automation, and performance monitoring
Experience designing and building microservices, APIs, and distributed systems
Solid understanding of data systems, including relational and non-relational databases, and large-scale data processing
Strong problem-solving and debugging skills across complex, distributed environments
Excellent communication and collaboration skills, with the ability to work effectively across teams and geographies
Nice-to-Have / Preferred Skills
Experience building AI systems with data ingestion, preprocessing, and feature engineering pipelines
Experience applying CI/CD practices to AI delivery, including automation of build, test, and deployment workflows
Familiarity with observability and monitoring practices for production AI systems
Experience improving AI system robustness through evaluation, monitoring, and operational safeguards
Experience with cloud-native and DevOps technologies (e.g., Docker, CI/CD pipelines, PCF or other cloud platforms)
Familiarity with payments, analytics, or reporting platforms
Exposure to emerging AI-assisted development tools (e.g., GitHub Copilot, Cursor, Claude Code, CrewAI, n8n)
#AI1
#LI-FT1Mastercard is a merit-based, inclusive, equal opportunity employer that considers applicants without regard to gender, gender identity, sexual orientation, race, ethnicity, disabled or veteran status, or any other characteristic protected by law. We hire the most qualified candidate for the role. In the US or Canada, if you require accommodations or assistance to complete the online application process or during the recruitment process, please contact reasonable_accommodation@mastercard.com and identify the type of accommodation or assistance you are requesting. Do not include any medical or health information in this email. The Reasonable Accommodations team will respond to your email promptly.

Corporate Security Responsibility

All activities involving access to Mastercard assets, information, and networks comes with an inherent risk to the organization and, therefore, it is expected that every person working for, or on behalf of, Mastercard is responsible for information security and must:

• Abide by Mastercard's security policies and practices;

• Ensure the confidentiality and integrity of the information being accessed;

• Report any suspected information security violation or breach, and

• Complete all periodic mandatory security trainings in accordance with Mastercard's guidelines.

In line with Mastercard's total compensation philosophy and assuming that the job will be performed in the US, the successful candidate will be offered a competitive base salary and may be eligible for an annual bonus or commissions depending on the role. The base salary offered may vary depending on multiple factors, including but not limited to location, job-related knowledge, skills, and experience. Mastercard benefits for full time (and certain part time) employees generally include: insurance (including medical, prescription drug, dental, vision, disability, life insurance); flexible spending account and health savings account; paid leaves (including 16 weeks of new parent leave and up to 20 days of bereavement leave); 80 hours of Paid Sick and Safe Time, 25 days of vacation time and 5 personal days, pro-rated based on date of hire; 10 annual paid U.S. observed holidays; 401k with a best-in-class company match; deferred compensation for eligible roles; fitness reimbursement or on-site fitness facilities; eligibility for tuition reimbursement; and many more. Mastercard benefits for interns generally include: 56 hours of Paid Sick and Safe Time; jury duty leave; and on-site fitness facilities in some locations.

Pay Ranges

O'Fallon, Missouri: $115,000 - $184,000 USD