COBOL Backend Developer (IBM z/OS Mainframe)

Quick Facts

• Role: COBOL Backend Developer (IBM z/OS Mainframe)

Description

You will create, develop, and maintain backend applications on the IBM z/OS mainframe using COBOL, CICS, DB2, APIs, and Assembler. The role includes implementing new business-driven functionality, writing maintainable code, participating in code reviews and refactoring/optimization, and supporting unit testing and documentation. You’ll also integrate services within a microservices architecture and work closely with business and technical stakeholders.

Responsibilities

• Develop and maintain COBOL backend applications on IBM z/OS mainframe

• Implement new functionality aligned with business requirements and system architecture

• Write high-quality, readable, maintainable code and continuously improve it

• Participate in code reviews and refactoring/optimization initiatives

• Develop and integrate services in a microservices architecture, collaborating on APIs

• Create and update technical and design documentation

• Prepare and execute unit tests; support software quality assurance

• Work with mainframe development/admin tools such as ISPF, SDSF, JCL, and z/OS Unix

• Collaborate with business analysts, IT architects, testers, and business representatives

• Analyze existing solutions and propose improvements to performance, stability, and quality

• Work in Jira and Confluence using good software engineering practices

• Share knowledge and mentor less experienced team members

Requirements

• Minimum 5 years of experience as a COBOL programmer

• Bachelor’s/Master’s degree in IT, mathematics, or a related field

• Hands-on IBM z/OS mainframe experience and strong knowledge of COBOL, CICS, DB2, API, and Assembler

• Comfort with ISPF, SDSF, and JCL; practical knowledge of z/OS Unix

• Knowledge of microservices architecture and distributed application development

• Ability to produce maintainable, high-performance code

• Experience designing technical solutions and preparing documentation

• Experience with unit testing and understanding of software quality

• Ability to collaborate with stakeholders across the project

• Experience using Jira and Confluence

• English proficiency sufficient to use technical documentation

• Independent, engaged, and well-organized working style

• Analytical problem-solving approach and willingness to find non-standard solutions

• Code review/refactoring experience (Git/Gerrit preferred)

Benefits

• B2B contract

• Access to the GIGLIKE benefits platform

• Hybrid work (1–3 days/week in the Warsaw office) or remote