MMS/RPG Engineer

CapNexus•New York, NY

3d•Remote

About The Position

CapNexus is an AWS consulting partner specializing in AI and cloud engineering. We build and deliver software through agentic engineering: we build and operate the systems that produce code, direct AI tooling to accelerate delivery, and exercise the judgment that keeps AI-generated work correct. Everyone at CapNexus works fluently inside our delivery system, which combines agentic tooling, spec-driven development, evidence-based quality, and AI-augmented delivery governance. CapNexus is looking for a Senior Software Engineer to own complex software outcomes: designing and building applications, APIs, and services, and raising the bar for the engineers around you. You'll work through our agentic delivery system, where AI tooling carries the mechanical load and you own the architecture, the correctness of what ships, and the growth of the people you mentor. We care more about how you think about building systems than which language you learned first. In this role, you'll focus on IBM i: building and supporting RPG applications, the DB2 for i data behind them, and the integrations that connect them to the rest of the business.

Requirements

5+ years of professional software engineering experience.
A strong grasp of architecture concepts: event-driven and service-based design, API design, data modeling, separation of concerns, and designing for change.
Experience owning a significant system from design through production, and mentoring the engineers who built it with you.
Working knowledge of CI/CD and infrastructure as code.
Hands-on experience with spec-driven or agentic development workflows, where specs drive code generation, for example Kiro, Claude Code, Amazon Q Developer, or Cursor with rules. Using AI only for autocomplete or snippets doesn't count.
A track record of catching what AI-generated or refactored code gets quietly wrong, and of building the tests and gates that prove behavior is preserved.
Hands-on experience programming on IBM i (AS/400, iSeries): free-format RPGLE, SQLRPGLE, CL, and OS/400 commands.
Strong SQL skills on DB2 for i, plus working knowledge of DDS, subfiles, and older RPG (RPG III and fixed format).
Experience with IBM i Access Client Solutions or iSeries Navigator, the IFS, and JSON and XML.

Nice To Haves

Experience with AWS or application modernization, such as integrating IBM i applications with AWS services or moving IBM i workloads to modern platforms.
Experience with Java, including Java on IBM i or RPG-to-Java modernization.
Experience supporting IBM i in an enterprise data center.
Background in retail.
Experience with Blue Yonder (JDA) MMS.

Responsibilities

Build and maintain IBM i applications in free-format RPGLE, SQLRPGLE, and CL, using ILE concepts such as procedures, service programs, and modules.
Work with DB2 for i through SQL and DDS, including physical and logical files and subfiles.
Integrate IBM i applications with other systems through web services, JSON and XML, FTP, and the Integrated File System (IFS).
Support changes through testing, deployment, and post-deployment, and resolve technical issues directly with client teams.
Set coding and testing standards for IBM i work, and identify where modernizing an application pays off.
Own the technical outcome for a system area or major feature set: propose the approach, define the task breakdown, and deliver with minimal escalation.
Design APIs and data models that account for cost, scale, and failure, and build in observability (logging, tracing, and metrics) from the start.
Work with Cloud Engineers on infrastructure as code and CI/CD so what you build deploys the same way every time.
Partner with the Solutions Architect on solution design and with the Engagement Manager on delivery, and turn designs into a build plan the team can execute.
Set code-quality standards for your area, and mentor Software Engineers I and II through pairing and reviews that teach, including how to direct AI tooling and check what it produces.
Join architecture presentations and technical deep-dives alongside the Solutions Architect when the client needs your depth.
Own outcomes on complex work, exercise architectural judgment, and raise the bar for those around you.
Set the tooling approach for a codebase or engagement: which work goes to a conversion engine, which is spec-driven build, where the human-in-the-loop gates belong, and how the toolchain is wired for the problem at hand.
Own the quality of the handoff from specification to build. Make sure specs are executable and actually satisfy the requirements, and hold delivered work to a defined readiness bar. When generated code is wrong, fix the spec, not just the output.
Be the final judgment on correctness for high-risk changes, including in unfamiliar domains, by designing the evidence that proves behavior is preserved.
Design and maintain the project-specific setup of our delivery tooling (steering, agent roles, templates, quality gates, and metrics) as durable capability, not one-off scaffolding.
Tooling does the mechanical work; you're accountable for whether it's right.