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

Software Engineer II

O Fallon, MO · On-site

$91K - $124K/yr

Our patented Java-based platform processes billions of transactions per month in tens of ... MasterCard software engineering teams leverage Agile development principles, advanced development ...

Senior Software Engineer

O Fallon, MO · On-site

$114K - $151K/yr

About the Role As a Java Site Reliability Engineer (SRE) within the Mastercard Send team, you will ... You will combine strong software engineering expertise with operational excellence practices to ...

Software Engineer

Saint Louis, MO · On-site

$60 - $65/hr

Software Engineer Job Location: St Louis, MO Job Type: Contract Job Overview: Pay Range: $60.00hr ... Recent experience in Java, Kotlin, Oracle, Postgres, Data handling, Spring, Spring Boot. * Recent ...

Senior Java Developer

Saint Louis, MO · On-site

$55.75 - $71/hr

Senior Java Developer St Louis, MO (Onsite from day 1) Interview Process: 3 rounds will be Zoom ... Grasp of software engineering skills in modular design, data structures, algorithms. Deep knowledge ...

Software Engineer II

O Fallon, MO · On-site

$91K - $124K/yr

Our patented Java-based platform processes billions of transactions per month in tens of ... MasterCard software engineering teams leverage Agile development principles, advanced development ...

Software Engineer II

O Fallon, MO · On-site

$91K - $124K/yr

Our patented Java-based platform processes billions of transactions per month in tens of ... MasterCard software engineering teams leverage Agile development principles, advanced development ...

Software Engineer II

O Fallon, MO · On-site

$91K - $124K/yr

Our patented Java-based platform processes billions of transactions per month in tens of ... MasterCard software engineering teams leverage Agile development principles, advanced development ...

Software Engineer II

O Fallon, MO · On-site

$91K - $124K/yr

Our patented Java-based platform processes billions of transactions per month in tens of ... MasterCard software engineering teams leverage Agile development principles, advanced development ...

Senior Java Developer

Saint Louis, MO · On-site

$55.75 - $71/hr

Senior Java Developer St Louis, MO (Onsite from day 1) Interview Process: 3 rounds will be Zoom ... Grasp of software engineering skills in modular design, data structures, algorithms. Deep knowledge ...

Role Software Development & Design Design, develop, test, and maintain high-quality Java-based software components that meet engineering and business requirements. Apply software design principles to ...

Role Software Development & Design • Design, develop, test, and maintain high-quality Java-based software components that meet engineering and business requirements. • Apply software design ...

Software Engineer II

O Fallon, MO · On-site

$91K - $124K/yr

... Java, Java/J2EE, Linux, Oracle, and SQL programming. • Strong knowledge of Java, Spring Boot ... software design, code reviews, testing, troubleshooting, and operational support. • Strong ...

Software Engineer II

O Fallon, MO · On-site

$91K - $124K/yr

Title and Summary Software Engineer II Overview: At Mastercard, our industry expertise is enhanced ... Strong technical experience with Java, Java/J2EE, Linux, Oracle, and SQL programming. Strong ...

Showing results 41-60

Java Software Engineer information

See O Fallon, MO salary details

$24

$56

$79

How much do java software engineer jobs pay per hour?

As of Sep 9, 2026, the average hourly pay for java software engineer in O'Fallon, MO is $56.50, according to ZipRecruiter salary data. Most workers in this role earn between $46.54 and $63.85 per hour, depending on experience, location, and employer.

What does a Java software engineer do?

A Java software engineer designs and develops computer applications using the Java programming language. In this job, you work with web developers and other software engineers to integrate java software into online platforms or other types of computer software. You are present for the entire development lifecycle, from design through quality testing. Your other duties may include documenting the programming code for other users or developers and writing reports to management or department heads. Java engineers work in large teams, so you must be able to collaborate with many people to complete a project.

What does a Java software engineer do?

A Java Software Engineer is responsible for designing, developing, and maintaining software applications using the Java programming language. They work on building efficient, scalable, and robust systems, often collaborating with other developers, testers, and stakeholders. Their tasks can include writing code, debugging, testing, and optimizing Java applications for various platforms, such as web, mobile, or enterprise environments. Java Software Engineers also help ensure that software solutions meet client or business requirements and adhere to industry best practices.

What are some typical challenges Java software engineers face when working on large-scale enterprise applications?

Java Software Engineers working on large-scale enterprise applications often encounter challenges such as managing complex codebases, ensuring high performance under heavy loads, and maintaining backward compatibility during system upgrades. Collaborating with cross-functional teams, like QA and DevOps, to streamline deployments and resolve integration issues is common. Additionally, keeping up with evolving frameworks and best practices is important for maintaining code quality and system reliability.

What are the key skills and qualifications needed to thrive as a Java software engineer, and why are they important?

To thrive as a Java Software Engineer, you need strong programming skills in Java, a solid understanding of object-oriented design, and typically a degree in computer science or a related field. Familiarity with development tools such as Eclipse or IntelliJ IDEA, version control systems like Git, and frameworks such as Spring or Hibernate is often required. Analytical thinking, problem-solving abilities, and effective teamwork distinguish high-performing individuals in this role. These skills ensure the efficient design, development, and maintenance of robust software applications in collaborative and dynamic technical environments.

What is the difference between Java Software Engineer vs Java Developer?

AspectJava Software EngineerJava Developer
Required CredentialsBachelor's in Computer Science, Java certificationsBachelor's in Computer Science, Java certifications
Work EnvironmentDesigning, developing, and testing Java applicationsWriting, debugging, and maintaining Java code
Employer & Industry UsageTech companies, software firms, enterprise solutionsStartups, software companies, freelance projects
Common Search & ComparisonOften compared for roles involving system design and architectureFocused on coding and implementation tasks

While both roles require similar skills and certifications, Java Software Engineers typically focus on designing and architecting Java applications, whereas Java Developers primarily concentrate on coding and maintaining Java programs. The choice depends on the project scope and career focus.

What are popular job titles related to Java Software Engineer jobs in O'Fallon, MO?

For Java Software Engineer jobs in O'Fallon, MO, the most frequently searched job titles are:

What job categories do people searching Java Software Engineer jobs in O'Fallon, MO look for?

The top searched job categories for Java Software Engineer jobs in O'Fallon, MO are:

What cities near O'Fallon, MO are hiring for Java Software Engineer jobs?

Cities near O'Fallon, MO with the most Java Software Engineer job openings:

Infographic showing various Java Software Engineer job openings in O'Fallon, MO as of August 2026, with employment types broken down into 82% Full Time, 14% Part Time, and 4% Contract. Highlights an 85% Physical, 4% Hybrid, and 11% Remote job distribution, with an average salary of $117,521 per year, or $56.5 per hour.

Software Engineer II

O Fallon, MO • On-site

$91K - $124K/yr

Full-time

Medical, Dental, Vision, Life, Retirement, PTO

This job post has expired today. Applications are no longer accepted.


Job description

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

Software Engineer II

Overview
Who is Mastercard? Mastercard is a global technology company in the payments industry. Our mission is 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. With connections across more than 210 countries and territories, we are building a sustainable world that unlocks priceless possibilities for all.

The Fraud Products team (part of O&T) is developing new capabilities for MasterCard's Decision Management Platform, which serves as the core for multiple business solutions to combat fraud and validate cardholder identity. Our patented Java-based platform processes billions of transactions per month in tens of milliseconds using a multi-tiered, message-oriented approach for high performance and availability.

MasterCard software engineering teams leverage Agile development principles, advanced development, design and test automation practices, and an obsession over security, reliability, and performance to deliver solutions that delight our customers. We're looking for talented Software Testing Engineers to design and develop regression and integration test automation for fraud applications using advanced technologies that are revolutionizing payments.

  • Would you like to deliver industry leading solutions for fighting fraud?
  • Are you motivated by speeding business solutions to market?
  • Do you want to innovate, using cutting edge technologies on challenging business problems?
  • Do you want to work for a company that offers above and beyond benefits including paid parental leave, flexible work hours, gift matching, and even volunteer incentives while encouraging your own professional learning and development?
  • Do you thrive in a place where you are continuously learning more while growing your skills and career?

Mastercard software engineering teams leverage Agile development principles, advanced development practices, automation, and an obsession with security, reliability, scalability, and performance to deliver solutions that delight our customers.

Role

  • Successfully deliver as part of a team on major projects and complex assignments with broad scope and long-term business implications.
  • Design, develop, test, and maintain high-quality software solutions using Java and related technologies.
  • Contribute to software design and system architecture discussions to build scalable, resilient, and high-performing applications.
  • Build and enhance features, services, and APIs that support Mastercard's fraud prevention and payment processing platforms.
  • Develop and maintain automated unit, functional, and integration tests as part of the software development lifecycle.
  • Participate in code reviews to ensure software quality, maintainability, security, and adherence to engineering standards.
  • Collaborate with software engineers, quality engineers, product teams, and platform teams to deliver solutions efficiently.
  • Apply secure coding practices and engineering best practices throughout the development lifecycle.
  • Contribute to performance engineering efforts by identifying bottlenecks and implementing scalable solutions.
  • Design and build systems with strong operability, observability, monitoring, and reliability characteristics.
  • Assist with production support by troubleshooting complex issues, identifying root causes, and implementing sustainable solutions.
  • Continuously improve development, testing, deployment, and release automation processes.
  • Be an integral part of Agile SAFe discovery, elaboration, sprint planning, and delivery activities.
  • Communicate, collaborate, and work effectively in a global environment. ________________________________________ All

About You

  • Strong software development and testing experience, particularly using Java.
  • Experience designing, developing, testing, and supporting enterprise-scale software applications.
  • Strong understanding of object-oriented programming, software design principles, and commonly used design patterns.
  • Experience contributing to software architecture discussions and designing scalable, highly available distributed systems.
  • Experience developing automated unit, functional, and integration tests.
  • Knowledge of data structures, algorithms, and performance optimization techniques.
  • Familiarity with secure coding practices and application security fundamentals.
  • Experience performing code reviews and promoting software engineering best practices.
  • Strong troubleshooting and debugging skills with the ability to identify and resolve complex technical issues.
  • Experience analyzing application performance and optimizing systems for scalability and reliability.
  • Familiarity with multi-tier web applications and high-performance transaction processing systems.
  • Experience working with development, testing, and release teams in Agile environments.
  • Skilled at explaining technical problems clearly and succinctly.
  • Strong communication, collaboration, and organizational skills.
  • Self-motivated with a high degree of initiative and ownership.
  • Ability to learn quickly and work effectively within geographically distributed teams.
  • Knowledge of Agile software development practices, continuous integration, and test-driven development.
  • Bachelor's degree in Computer Science, Engineering, Information Systems, Information Technology, or equivalent practical experience. ________________________________________ Essential Skills

Required

  • Strong Core Java programming experience
  • Experience designing and developing enterprise software applications
  • Experience with Continuous Integration systems (e.g., Jenkins)
  • Oracle, PL/SQL, and advanced SQL scripting
  • Experience with code reviews and software development best practices
  • Knowledge of software design principles and object-oriented design
  • Experience with automated unit, functional, and integration testing
  • Experience with Testing frameworks such as TestNG and Spock
  • Knowledge of secure coding practices
  • Experience with production troubleshooting and root cause analysis
  • Knowledge of Splunk, including dashboards, alerts, and monitoring
  • Experience with IDEs such as IntelliJ IDEA or JBoss Developer Studio ________________________________________ Preferred

Skills

  • Experience with distributed systems at scale
  • Experience contributing to software architecture and scalability initiatives
  • Knowledge of performance engineering and application optimization
  • Experience designing observable and operationally resilient systems
  • Experience using tools such as Postman, PuTTY, WinSCP, and Toad
  • Experience working within cloud-native or microservices-based environments

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: $92,000 - $147,000 USD