National Australia Bank accelerates legacy migrations with Cursor

Summary

NAB standardized 6,000 developers on Cursor after evaluating Amazon Q and GitHub Copilot, and is expanding access to more than 10,000 technology employees. The bank uses Cursor across legacy modernization and new development: BizCalc's Silverlight/.NET monolith is being refactored into Java microservices and React, while Assembly-based core-banking programs are being migrated using generated flowcharts and business summaries. Engineers use Ask Mode, Plan Mode, custom NAB CEL skills, Composer, and Opus coding models to document systems, produce requirements and API specifications, parallelize implementation, and test changes. NAB reports that both modernization efforts are progressing three times faster than expected, while a hardware-agnostic payment app was built in under three weeks rather than four months; one team reported a 5–8x velocity improvement.

Takeaways

1. 1

   NAB CEL uses Cursor primitives including rules, skills, and hooks to centralize shared knowledge, enforce development standards, and set guardrails for agent behavior.

2. 2

   For the BizCalc migration, Cursor reduced pre-development work from an originally planned two months to one week; the full Java and React migration is expected to take two months instead of six.

3. 3

   The merchant services team built a hardware-agnostic payment app in less than three weeks using Composer and Opus after creating a plan for parallelized subagent work; the team reported a 5–8x velocity improvement.