Senior Software Engineer

mastercard· US: Mastercard Technologies, LLC
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📍 O'Fallon, MissouriFull time

About this role

Our Purpose

Mastercard powers economies and empowers people in 200+ countries and territories worldwide. Together with our customers, we’re helping build a sustainable economy where everyone can prosper. We support a wide range of digital payments choices, making transactions secure, 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 Engineer

Who is Mastercard?

We work to connect and power an inclusive, digital economy that benefits everyone, everywhere, by making transactions safe, simple, smart, and accessible. Using secure data and networks, partnerships, and passion, our innovations and solutions help individuals, financial institutions, governments, and businesses realize their greatest potential. Our decency quotient, or DQ, drives our culture and everything we do inside and outside of our company. We cultivate a culture of inclusion for all employees that respect their individual strengths, views, and experiences. We believe that our differences enable us to be a better team – one that makes better decisions, drives innovation, and delivers better business results.

About the Role

This is an exciting opportunity for you to join Mastercard’s Transaction Switching program and improve authorization response time. Authorization sends billions of transactions among the integrated issuers, acquirers, and service providers worldwide. This position is on the performance engineering team in O’Fallon, Missouri and will partner with the development teams to performance test and tune each release. We are looking for software engineers that are passionate about creating high quality software while keeping performance top of mind.

• Do you have a passion for solving complex technical challenges?
• Do you love learning new technologies and apply it to your team?
• Have you developed software before – preferably in C/C++?
• Have you spent time in Linux environments?
• Have you created scripts to automate manual tasks (i.e. shell script, TCL, Perl, Python)?
• Do you understand throughput, latency, memory and CPU utilization?
• Do you have experience and prefer working in an Agile environment?

Role

• Work closely with feature teams to identify risks and anticipate problems to ensure that each release does not negatively impact performance
• Dig into the code to determine performance bottlenecks and make the improvement
• Design, configure, automate, and execute performance tests
• Improve the performance environment with your own code, automation, and onboarding of external tools (i.e. Dynatrace and Splunk)
• Work collaboratively and effectively in a fast-paced environment

All About You

• Proven experience developing backend applications in a Linux environment with C and/or C++ programming language(s)
• Deep knowledge and experience of computer architecture with throughput, latency, memory and CPU utilization for performance engineering to test, debug and troubleshoot performance issues.
• Clear experience with automation to create scripts for manual tasks (I.e., shell scripting, TCL, Perl, Python)



#AI3

Mastercard 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

Frequently Asked Questions

Is the salary disclosed for the Senior Software Engineer position at mastercard?
The salary for this Senior Software Engineer role at mastercard is not publicly listed. Click "Apply Now" to learn more about the compensation package on their official careers page.
Where is the Senior Software Engineer position at mastercard located?
This Senior Software Engineer role at mastercard is based in O'Fallon, Missouri. The position is listed as on-site or hybrid. Check the full job description or apply directly to confirm the work arrangement.
Is the Senior Software Engineer role at mastercard full-time or part-time?
This is listed as a Full time position. It is posted as a Senior Software Engineer role in the US: Mastercard Technologies, LLC department at mastercard.
Which team or department does the Senior Software Engineer at mastercard belong to?
This Senior Software Engineer position is part of the US: Mastercard Technologies, LLC department at mastercard. See the full job description for more information about the team structure and responsibilities.
How do I apply for the Senior Software Engineer position at mastercard?
Click the "Apply Now" button on this page. You will be redirected to mastercard's official application portal hosted on workday where you can submit your application directly.
When was the Senior Software Engineer job at mastercard posted?
This Senior Software Engineer position at mastercard was posted on Aug 18, 2026. Apply as soon as possible — early applications are often reviewed first.
Senior Software Engineer
mastercard
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