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Senior Mainframe Developer Jobs in Missouri (NOW HIRING)

Stellar IT Group

Mainframe Developer

Saint Louis, MO · On-site

$47.75 - $61.25/hr

Mainframe Developer (Senior - Security Remediation) Location: Remote Duration: 6-12+ Months Contract Role Overview We are seeking experienced Senior Mainframe Engineers with deep expertise in legacy ...

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How much do senior mainframe developer jobs pay per hour?

As of Sep 15, 2026, the average hourly pay for senior mainframe developer in Missouri is $54.08, according to ZipRecruiter salary data. Most workers in this role earn between $50.72 and $59.09 per hour, depending on experience, location, and employer.

What is a senior mainframe developer?

Senior Mainframe Developers are experienced professionals who design, develop, and maintain mainframe systems—large-scale computers used by organizations for critical applications, bulk data processing, and enterprise resource planning. They are proficient in languages like COBOL, JCL, and Assembler, and often work with databases and transaction processing systems. Their responsibilities include troubleshooting system issues, optimizing performance, mentoring junior developers, and ensuring the reliability and security of mainframe operations.

What are some common challenges faced by senior mainframe developers when integrating legacy systems with modern technologies?

Senior Mainframe Developers often encounter challenges when integrating legacy mainframe systems with newer technologies such as cloud platforms, APIs, or microservices. These challenges include ensuring data consistency, maintaining system security, and minimizing downtime during migrations. Collaboration with cross-functional teams, such as infrastructure engineers and application developers, is key to developing seamless integration solutions. Staying up-to-date with modernization tools and best practices can help address these complexities and support the organization's digital transformation goals.

What are the key skills and qualifications needed to thrive as a senior mainframe developer, and why are they important?

To thrive as a Senior Mainframe Developer, you need deep expertise in mainframe programming languages (like COBOL, JCL, and PL/I), systems analysis, and a strong understanding of legacy application architectures, typically supported by a degree in computer science or related experience. Familiarity with tools such as IBM z/OS, DB2, CICS, and version control systems is essential, along with relevant certifications like IBM Certified System Programmer. Excellent problem-solving, communication, and leadership skills help you collaborate effectively and mentor junior developers. These skills are crucial for maintaining mission-critical systems, ensuring reliability, and guiding modernization efforts in complex enterprise environments.

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Infographic showing various Senior Mainframe Developer job openings in Missouri as of September 2026, with employment types broken down into 86% Full Time, 5% Part Time, and 9% Contract. Highlights an 77% Physical, 5% Hybrid, and 18% Remote job distribution, with an average salary of $112,482 per year, or $54.1 per hour.

Mainframe Developer

Saint Louis, MO • On-site

Stellar IT Group
See more jobs at Stellar IT Groupexternal

$47.75 - $61.25/hr

Contractor

Re-posted 3 days ago

Job description

Overview:
Position: Mainframe Developer (Senior - Security Remediation)
Location: Remote
Duration: 6-12+ Months Contract
Role Overview
We are seeking experienced Senior Mainframe Engineers with deep expertise in legacy banking systems to investigate, understand, and safely remediate security vulnerabilities in production-critical applications. This role requires strong proficiency in COBOL, CICS, DB2, and z/OS, along with the ability to navigate complex, decades-old financial systems where stability and accuracy are paramount. The ideal candidate will be a hands-on engineer who can trace vulnerabilities to their root cause, implement secure fixes, and ensure safe deployment without disrupting mission-critical banking operations.
Key Responsibilities
  • Investigate and analyze security vulnerabilities within legacy mainframe banking applications.
  • Trace issues to their technical root cause and design secure remediation strategies.
  • Modify and enhance COBOL, CICS, and DB2 codebases while ensuring production stability.
  • Collaborate with security, infrastructure, and application teams to validate fixes.
  • Conduct secure coding reviews and enforce mainframe security best practices.
  • Provide production support for remediation deployments, ensuring minimal disruption.
  • Document remediation steps, secure design patterns, and operational improvements.
  • Contribute to strengthening long-term resilience of legacy banking systems.
Required Skills
  • Strong expertise in COBOL, JCL, CICS, DB2, z/OS.
  • Deep understanding of mainframe application architecture and legacy banking systems.
  • Hands-on experience with secure coding practices in mainframe environments.
  • Proven ability to remediate vulnerabilities in production-critical systems.
  • Strong problem-solving skills and ability to work independently in high-stakes environments.
Preferred Skills
  • Experience with large-scale financial or banking applications.
  • Familiarity with mainframe modernization initiatives.
  • Exposure to secure SDLC practices and vulnerability management frameworks.
  • Strong communication skills to bridge security and engineering teams.

Skills:
Mainframe,cobol,aws

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