Can an existing system be taken over and further developed?

The usual process

1. Inventory

What code is available, which dependencies are outdated, are there tests, how is it delivered, where are the data? This review takes a few days and answers the core question: take over or rebuild.

2. Stabilize

First, address the risks: outdated dependencies with known vulnerabilities, missing backups, unprotected access. No new features yet.

3. Secure

Automated tests for critical processes – ensuring future changes do not silently break something.

4. Further Development

Only now, new features are added step by step.

Why rebuilding is usually the worse choice

An evolved system may appear messy from the outside. Much of this mess, however, consists of special cases that arose over years and were resolved. Those who rebuild do not include these special cases – and encounter them all again, individually, in production.

Moreover: During the rebuild, the old system must continue running and be maintained. You pay twice.

When rebuilding is still the right choice

• The used technology is no longer supported and cannot be updated
• There is no source code left
• The business model fundamentally no longer matches the business
• The effort for each small change is demonstrably higher than a rebuild

These are four clear criteria. "The code is unattractive" is not one of them.