Start with the boundaries
Map users, modules, integrations, scheduled jobs, reports and business-critical data flows. The modernization plan is only safe when the team understands what depends on what.
Create a stable integration layer
APIs can give new applications a controlled way to use existing business logic or data while older screens remain operational.
Replace visible pain first when appropriate
A new frontend can improve usability and reduce support burden even while the backend remains in place. Other projects may need to begin with infrastructure or data reliability instead.
Move one workflow at a time
Parallel operation, reconciliation and explicit rollback plans make staged migration less dramatic than a big-bang launch.
Use the transition to reduce future coupling
The goal is not simply to move old code into a newer framework. The new architecture should create clearer boundaries so the next change is easier than the last one.