Freelance Junior Java Developer Jobs in Missouri

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?
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
We are seeking a Senior Software Engineer to join our File Transfer platform team, responsible for building and operating missioncritical, highly available services that support secure, largescale data movement across global environments. This role is handson and requires deep expertise in Java and Springbased platforms, strong engineering ownership, and the ability to collaborate effectively with distributed teams in an agile delivery model.
Role
Design, build, and maintain highly available, resilient Java Springbased services supporting enterprisegrade file transfer workloads.
Contribute to the endtoend lifecycle of platform capabilities, from design and development through production support and continuous improvement.
Build systems with a strong focus on reliability, scalability, security, and performance, suitable for missioncritical environments.
Partner with global engineering, SRE, product, and operations teams to deliver features and resolve complex production issues.
Drive engineering best practices, including code quality, automated testing, CI/CD, and operational readiness.
Participate actively in agile ceremonies (sprint planning, reviews, retrospectives) and contribute to continuous delivery.
Support platform observability, incident analysis, and postincident improvements to reduce operational risk.
Mentor junior engineers and contribute to a culture of technical excellence and ownership.
All About You
Strong written and verbal communication skills, with the ability to clearly articulate technical concepts and collaborate across functions.
Handson experience building backend platforms using Java and Spring (Spring Boot preferred).
Knowledge working with event driven platforms, such as Apache KAFKA, RabbitMQ, NATS, or other equivalents.
Experience working with Cloud Services, such as AWS, GCP, Azure, or PCF.
Proven experience developing and operating missioncritical, highly available systems in production environments.
Strong understanding of distributed systems, including scalability, fault tolerance, concurrency, and performance tuning.
Experience working with global, geographically distributed teams.
Solid experience working in an agile (Scrum / SAFe) environment.
Demonstrate a sense of ownership and accountability for delivered software and operational outcomes.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