Insight

Legacy System Modernization: When to Rebuild or Integrate

A practical modernization guide for teams deciding between replacing, integrating, or improving existing systems.

Key points

The decision framework weighs business continuity, undocumented behavior, data risk, integration options, support constraints, and the value of replacing only the parts that limit change.

  • Rebuild when the old system blocks growth or security
  • Integrate when core workflows still work
  • Modernization can happen in phases

How i-360 applies this thinking

The modernization choice should consider business-critical logic, code and data condition, integration options, security exposure, supportability, user disruption, migration risk, and the cost of delaying change.

Next step

Inventory the application, runtime, database, interfaces, users, critical workflows, defects, reports, deployment constraints, and known areas where documentation or technical ownership is missing.

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