Legacy Software Modernization
We rescue your legacy software. Modernization, refactoring, and cloud migration for outdated applications – without disrupting ongoing operations.
Trusted by leading companies
Technical debt is slowing you down
Your application has been running for 10 years and generates revenue. But: "Never touch a running system" is no longer a motto – it's become a survival strategy. Outdated libraries no longer receive security updates. New developers can't navigate the spaghetti code or they quit.
The database is the bottleneck, scaling is impossible. Performance issues are piling up. You know: This can't go on. But a complete rebuild is risky and expensive. What to do?
Dev + Ops Under One Roof
Most agencies can only build new. We can operate legacy systems AND modernize them. Thanks to Linux kernel expertise, CI/CD pipelines, and parallel operations, we ensure the old app stays stable while the new one emerges.
Our Modernization Services
Code & Infrastructure Audit
We analyze your source code with static code analysis (SonarQube), identify the biggest risks, and create a prioritized modernization roadmap.
Containerization (Lift & Shift)
We package your legacy app in Docker containers. Your 10-year-old app runs safely on modern servers – with all its old dependencies.
Strangler Fig Pattern
Instead of a big-bang rewrite, we build new features as modern microservices alongside the old app. An API gateway decides which traffic goes where.
Database Modernization
Migration from old MySQL/Oracle to modern PostgreSQL solutions. Including schema migration, data cleaning, and query optimization.
Code Refactoring
Gradual introduction of typing (PHP Type Hints, TypeScript), tests, and clean code patterns. Spaghetti becomes readable and maintainable.
CI/CD Pipeline Setup
From FTP uploads to automated deployments. We set up GitLab/GitHub pipelines that automate the transition and catch errors early.
Security Hardening
EOL PHP and Java versions without security updates? We migrate to current versions or isolate the app in protected containers.
Team Enablement
We work as an expert team for the difficult architectural changes. Your team learns alongside and gradually takes over – no vendor lock-in.
Monitoring & Observability
Introduction of modern logging, metrics, and tracing. Finally see what's happening in your application – instead of just guessing.
Before → After
Legacy (Your Current State)
Modern (Our Goal)
The specific migration depends on your existing stack. We analyze and recommend individually.
We don't suggest throwing everything away. We use proven patterns.
Strangler Fig Pattern
Gradual ReplacementInstead of a "Big Bang" rewrite, we build new features as modern microservices alongside the old app.
An API gateway (Traefik/Nginx) decides: Old traffic → Old App. New traffic → New Service. The new architecture gradually "strangles" the old software.
Database Modernization
Data MigrationWe migrate your data from outdated, unmanaged databases (old MySQL/Oracle) to modern, scalable solutions.
Schema migration, data cleaning, and query optimization for Managed PostgreSQL (Supabase/Hetzner) or time-series DBs.
How can we help you?
Frequently Asked Questions
Answers to the most important questions about legacy modernization
Topics
Strategy & Risk
No. A complete rewrite ("Big Bang") often fails. We recommend an iterative approach (e.g., Strangler Pattern). We stabilize the core and gradually migrate individual modules (e.g., billing, user auth) to new services.
No, these versions are "End of Life" (EOL) and no longer receive security updates. We can first package the application in protected Docker containers to mitigate the immediate risk, then plan the upgrade to PHP 8.x.
Yes. We analyze the code, perform static code analysis (SonarQube), and gradually introduce typing (e.g., PHP Type Hints, TypeScript) and tests to make the code readable and maintainable.
We use "Blue/Green Deployments" and load balancers. The old and new versions run in parallel. We gradually switch traffic over. If something goes wrong, we immediately switch back (rollback).
That's the norm. We perform reverse engineering, analyze code without documentation, and create up-to-date architecture documentation. This makes the knowledge accessible again – independent of any individuals.
Infrastructure & Containers
It decouples your software from the server. Old software often needs old libraries (libssl, glibc) that are missing on modern servers. In a container, we include these dependencies. Your 10-year-old app runs safely on a brand-new high-speed server.
Yes. The first step is often introducing Git. We import your code, set up repositories (GitLab/GitHub), and define branching strategies so multiple developers can work safely in parallel again.
Yes. Data is gold. We write scripts that extract data from old schemas, clean it (fix encoding errors, normalization), and transfer it to modern databases (PostgreSQL).
We document all existing APIs and integrations during the audit. During migration, we ensure all interfaces (ERP, CRM, payment providers) continue to work. Often we even improve them with clean REST/GraphQL APIs.
Frontend & UI
Yes. We can keep the backend (logic) but build a modern API in front of it. We then add a contemporary frontend with React or Vue.js. The software feels new to users without rewriting the core ("Headless" approach).
We're not dogmatic. For many SMBs, a well-structured Modular Monolith is better than 50 complex microservices. We choose the architecture that fits your team size.
Process & Costs
With a Code & Infrastructure Audit. We examine the source code and servers, identify the biggest risks ("low-hanging fruit"), and create a modernization roadmap.
Absolutely. We often work as an "expert team" handling the difficult architectural changes and introducing CI/CD, while your team continues daily operations and learns from us ("enablement").
It's cheaper than a complete rebuild, but still an investment. Since we work incrementally, you have monthly predictability instead of a massive upfront investment.
It depends on scope. Containerization (Lift & Shift) can be done in a few weeks. A complete Strangler Fig migration can take 6-18 months – but you'll see results after the first sprint.
Yes. We take over operations and bug fixing of the legacy application (maintenance) so your team can focus. This allows us to modernize in parallel without affecting day-to-day business.
Industry-leading companies rely on us
What do our customers say?
Let's Talk About Your Idea
Whether a specific IT challenge or just an idea – we look forward to the exchange. In a brief conversation, we'll evaluate together if and how your project fits with WZ-IT.
Trusted by leading companies
Timo Wevelsiep & Robin Zins
CEOs of WZ-IT