Software2025-10-116 min read

Legacy System Modernisation: A Step-by-Step Guide

That old system running your business might work, but it's probably costing you more than you think.

Signs You Need Modernisation

Modernisation Approaches

1. Encapsulation

Wrap the legacy system with APIs so new applications can interact with it.

2. Replatforming

Move to modern infrastructure with minimal code changes.

3. Refactoring

Restructure and optimise code while preserving functionality.

4. Rebuilding

Rewrite from scratch using modern technologies.

5. Replacing

Replace with off-the-shelf software.

The Strangler Fig Pattern

Gradually replace legacy components with new ones, routing traffic to new services until the old system can be retired.

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