Mainframe Legacy Systems Developer; Assembler​/COBOL​/Systems

Position: Mainframe Legacy Systems Developer (Assembler/COBOL/Systems)
TILO DYNAMICS LLC Mainframe Legacy Systems Developer (Assembler/COBOL/Systems) Remote
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Tilo Dynamics LLC is seeking an experienced Mainframe Legacy Systems Developer to support a large government modernization effort. This role focuses on analyzing, maintaining, and reverse engineering legacy mainframe modules (Assembler, COBOL, JCL) and assisting with their conversion to modern Java-based systems. You will work with a team of engineers to understand existing business logic, document legacy code, and guide the design of equivalent solutions in modern environments.

About

TILO DYNAMICS LLC

Tilo Dynamics is a Washington, DC–based professional services firm specializing in IT, data analytics, systems engineering, and staffing solutions. As a Certified Business Enterprise (CBE), we partner with government agencies and private sector organizations to deliver innovative, cost-effective results. Our team brings a blend of technical expertise and human-centered problem solving, with a strong commitment to quality, collaboration, and client success.

Description

Responsibilities

• Analyze and document existing mainframe modules (Assembler, COBOL, or other low-level code).
• Design, develop, and maintain JCL and mainframe processes to meet project requirements.
• Reverse engineer undocumented code to extract business logic and processing rules.
• Collaborate with Java developers to ensure accurate conversion of legacy code.
• Support modernization by translating legacy data and workflows into scalable Java solutions.
• Work within Agile teams, contributing to sprints, planning, and peer reviews.
• Provide technical guidance on mainframe systems and assist with testing, validation, and integration.

Qualifications

Required

• 5+ years of experience in mainframe software development (Assembler, COBOL, PL/I, or related).
• Proficiency in JCL and mainframe environments (z/OS, MVS, or equivalent).
• Strong skills in analyzing and reverse engineering legacy applications.
• Experience supporting large-scale government or enterprise systems.
• Excellent documentation and communication skills; ability to explain legacy logic to modern development teams.

Preferred

• Familiarity with Assembler Language Code (ALC).
• Experience with IRS systems (BMF, IMF, CADE2) or other federal financial systems.
• Existing or prior IRS MBI clearance.
• Experience assisting with legacy-to-Java or legacy-to-cloud migration projects.
• Bachelor’s degree in Computer Science, Engineering, or related field (or equivalent experience).

Why Join Us

At Tilo Dynamics, we specialize in IT, data analytics, systems engineering, and staffing solutions for federal and commercial clients. As a Certified Business Enterprise (CBE) based in Washington, DC, we bring technical expertise, flexibility, and a deep commitment to quality results.

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