In this episode of the Vertali Podcast, host Ed Nell talks with senior software developer Nathan Carroll about how AI is changing mainframe software development, from day-to-day tooling to security, governance, and the shifting role of developers. 

Nathan shares how he uses AI as a “rubber duck” for high-level architecture, why agentic AIs increasingly feel like junior team members, and how well-placed guardrails and human review keep velocity gains from becoming security liabilities. He also digs into mainframe-specific realities (limited public training data, on-prem needs) and why modernization efforts like documentation and UI overhauls are where AI shines today.

Key Takeaways

AI as a learning accelerator: For self-taught or cross-discipline developers, AI is a powerful training and upskilling companion that exposes better patterns and practices.

Pick the right tool for the job: Nathan uses ChatGPT for architectural discussion and ideation (not code), GitHub Copilot for inline acceleration, and Claude for documentation/UI work.

Guardrails + review are non-negotiable: Senior review, clear role/instructions, and “ask clarifying questions” policies sharply improve quality and safety. Treat AI like a junior hire.

Security first: Biggest risk is unintentional secrets exposure in generated/committed code; enforce credential handling, redaction, and enterprise/onsite deployments.

Best Moments

“AI is great at boilerplating, explaining code, and small actionable tasks.”

“We rewrote the whole thing using React in about three months… AI was pivotal.”

“Treat it like a junior developer, don’t let it go crazy, and always review.”

“Have a human in the chain… don’t assume the AI knows what it’s doing.”

About Vertali

Vertali is a leading cyber security company specialising in IBM® mainframe infrastructure. With deep expertise, innovative software, and trusted resources, Vertali supports organisations across the UK and globally, particularly in finance, retail, utilities, and government sectors.

100% focused on mainframe systems, Vertali helps organizations secure and optimize their operations. By combining advanced technology with expert insights, Vertali delivers powerful cybersecurity solutions and consulting services that protect against evolving threats. Driven by a proactive approach, Vertali enables businesses to build resilient systems, safeguard sensitive data, and maintain smooth, uninterrupted operations in the face of cyber risks.

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