Jobs in O Fallon, MO
60 open roles — posted here, and found on employers' own careers sites.
Senior Specialist, Payroll Tax & M&A Integration
Mastercard
Full-time · O Fallon, MO · $85,000 – $132,000
This role leads payroll tax compliance and integration activities during corporate mergers and acquisitions, managing tax registrations, employee setup, vendor coordination, and post-implementation stabilization. It suits someone with deep payroll tax expertise who thrives managing complex multi-jurisdictional projects through organizational change.
Listed on Mastercard’s careers site · Apply there ↗
Site Reliability Engineer II
Mastercard
Full-time · 2 locations · $76,000 – $127,000
Mastercard's Business Operations team seeks a Site Reliability Engineer to design and implement CI/CD pipelines, automate DevOps processes, and lead reliability improvements across the organization. This role suits someone passionate about automation, distributed systems, and solving complex infrastructure problems across global teams.
Listed on Mastercard’s careers site · Apply there ↗
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Principle, Vulnerability Analyst
Mastercard
Full-time · O Fallon, MO · $152,000 – $258,000
A Principal-level security analyst role focused on validating AI-generated vulnerability findings and driving their remediation across Mastercard's software environment. This position suits experienced security professionals who can bridge AI model outputs and engineering teams, making technical risk decisions and improving security processes at scale.
Listed on Mastercard’s careers site · Apply there ↗
Senior Software Engineer
Mastercard
Full-time · 17 locations · $115,000 – $184,000
A senior-level individual contributor role focused on designing and building scalable distributed systems while mentoring junior engineers. This position suits experienced Java backend developers who want to take on architectural responsibilities and grow as technical leaders without moving into pure management.
Listed on Mastercard’s careers site · Apply there ↗
Manager - Franchise Customer Onboarding & Partnerships NAM
Mastercard
Full-time · O Fallon, MO · $117,000 – $193,000
Mastercard seeks an experienced manager to oversee customer onboarding, compliance, and partnerships for specialty merchants and service providers across North America. This role combines stakeholder management, regulatory oversight, and process improvement for a global payments company.
Listed on Mastercard’s careers site · Apply there ↗
Lead PostgreSQL Engineer
Mastercard
Full-time · O Fallon, MO · $122,000 – $207,000
Lead a team designing and operating Mastercard's enterprise PostgreSQL databases at scale, combining deep database expertise with platform engineering practices to build secure, highly available services. This role suits experienced database engineers ready to drive technical strategy and mentor others across cloud infrastructure and distributed systems.
Listed on Mastercard’s careers site · Apply there ↗
Lead Software Engineer (C/C++)
Mastercard
Full-time · O Fallon, MO · $140,000 – $231,000
Lead a critical team building the payment authorization system that processes billions of transactions globally, designing scalable solutions and mentoring engineers. Ideal for experienced C/C++ developers who thrive on complex performance challenges and want to shape technical direction in a secure, high-reliability environment.
Listed on Mastercard’s careers site · Apply there ↗
Director, Platform Engineering
Mastercard
Full-time · O Fallon, MO · $152,000 – $258,000
A leadership role directing platform engineering and infrastructure automation strategy at a global payments company, suited for experienced DevOps engineers ready to move into management and shape enterprise-wide automation standards.
Listed on Mastercard’s careers site · Apply there ↗
Manager, Software Engineering
Mastercard
Full-time · 5 locations · $140,000 – $231,000
Lead a software engineering team building fraud detection systems for one of the world's largest payment networks, responsible for strategy, delivery, and developing high-performing managers in a role that bridges technical depth with executive leadership.
Listed on Mastercard’s careers site · Apply there ↗
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Lead Software Engineer
Mastercard
Full-time · 9 locations · $168,000 – $277,000
A leadership engineering role at Mastercard where you'll architect complex distributed systems, guide technical teams, and drive organizational engineering standards across global payment infrastructure. This suits experienced engineers who thrive on mentoring others and making decisions that span multiple services and teams.
Listed on Mastercard’s careers site · Apply there ↗