Our world runs on IT built in the 80s and 90s by engineers who are now retiring. This is becoming very worrying for corporates who have critical systems running on legacy code that only a handful of people still understand.That's where GenAI arrives. With its almost magical transpilation abilities, it is the innovation that was needed to kickstart the legacy modernisations that had been postponed for too long.Having worked on critical modernisations for more than 15 years, I jumped on the opportunity to experiment with how LLMs can accelerate complex migration projects. I will share the concrete experience we have accumulated on a wide range of stacks (Swift->React-Native, Eclipse RCP -> Spring Boot, Java 1.6 Spring -> Java 21 Spring Boot, PHP ZF1 -> Symfony 7), cover both the good surprises and the limitations that we uncovered, and share our current playbook to best leverage AI when migrating a legacy system.
