Marco Patzelt
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January 31, 2026
Updated: February 7, 2026

Legacy Modernization: Why Rewrites Fail, Middleware Wins

German Mittelstand runs on legacy. Agencies want full rewrites but the real value is in integration. A case for the middleware layer over the wrecking ball.

The Reality of the Economy

The Empathy Bridge: Why Legacy Exists

It is easy to mock SAP monoliths, 20-year-old Oracle databases, or Navision instances running on servers in a basement. The "Silicon Valley" mentality dictates: "It's old, it's trash, delete it."

But we must understand why these systems are still there. They are not there because the IT department is lazy. They are there because they work. These systems contain 15 years of process knowledge, millions of records, and business rules that keep the company alive. Telling a mid-sized company (Mittelstand) to rip out its heart just because the tech stack isn't "trendy" anymore is not just arrogant—it is bad business.

The "Vibe Coding" Delusion

This is where reality collides with the current AI euphoria. There is a new wave of developers—I call them the "Vibe Coding Bros"—who believe you can just "rebuild" a 50-million-euro company with enough prompts.

The Reality is Different:

  • Data Gravity: You don't just migrate 2 TB of customer data with complex relations into a NoSQL cloud database without losing data integrity.
  • Process Depth: The logic of why Client X gets a 3% discount, but only on Tuesdays, is often documented nowhere except in COBOL code from 1998.
  • Human Factor: Employees are trained on these screens. A complete rewrite means years of retraining and frustration.

I see agencies selling 6-month projects to rewrite everything. The result? After 2 years and burned budgets, the project is quietly buried. That is not engineering; that is negligence.

Architecture over Demolition

The Fix: The Middle Layer (The "Anti-Rewrite" Strategy)

If "Rewrite Everything" is not an option and "Keep Everything" means stagnation, what is the solution?

I don't sell migration. I sell a facade.

My approach is radically pragmatic: The legacy system stays exactly where it is. We accept it as the "System of Record". But we stop letting humans interact with it directly. Instead, we build a lean Orchestration Layer (Middleware) in front of it.

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How It Works:

  1. Legacy as API: We treat the old database or ERP system purely as a data source.
  2. The Translation: We build a Middleware (e.g., using Next.js API Routes or Supabase Edge Functions) that translates the cryptic legacy data (XML, SOAP, CSV) into clean, modern JSON.
  3. Modern Frontend: The user only interacts with a modern Web App (React/Next.js). They have no idea that a 20-year-old server is doing the heavy lifting in the background.

This is the sweet spot. You deliver a modern UX to the client in weeks, without the risk of a data migration. The background system can be slowly replaced over the next 5 years ("Strangler Fig Pattern")—but only after business value has been delivered.

(Hot Take): Anyone today trying to solve complex business logic in the Frontend or tinkering directly inside the Legacy System has misunderstood architecture. Logic belongs in the Middleware.

The Verdict

The Verdict: The Unsexy Goldmine

Why is everyone rushing into "Vibe Coding" and building new apps? Because it is easy. It is clean. No one wants to deal with SOAP headers or VPN tunnels.

But that is exactly why the money is here. The economy (especially the German Mittelstand) does not need new apps that no one uses. They need bridge-builders who can rescue their massive data reservoirs into 2024 without paralyzing operations.

The Playbook for Your Career:

  1. Don't just learn React; learn Integration Patterns.
  2. Understand SOAP, REST, XML, and SQL better than anyone else.
  3. Sell speed via Middleware, not perfection via Rewrites.

You won't be the coolest developer on Twitter. But you will be the one saving the system while the others are still prompting.

Code is a liability. Integration is the asset.

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