Connect data
Systems, tables, files and APIs are wired up to a reliable, observable data flow.
Modernise existing applications. Resolve SQL bottlenecks. Strengthen your development team.
Specialist in SQL performance and database optimisation. For around 30 years I have been making slow databases fast – often many times over, with a few targeted changes and without putting live operation at risk. See approach, cases and measurements →
I am Manuel Hagen, a freelance software engineer with a degree in business informatics. I combine an understanding of your business processes with C#/.NET, Blazor and SQL expertise – from analysing existing applications to tested implementation and handover to your team.
More than 30 years across IT, controlling and software development · Experience as technical app owner at NXP Semiconductors
- SQL & Databases
- Process Automation
- System Integration
- Custom Web Applications
Many companies have data. Few really use it efficiently.
Data is scattered across ERP systems, Excel files, line-of-business apps, databases and manual processes. The result: duplicated work, error-prone routines, slow reporting and decisions made on shaky ground. datrexx helps to close those gaps – with thoughtful data models, clean interfaces, automated processes and software that fits the way people actually work.
Automate processes
Recurring tasks become clear, traceable and maintainable logic.
Improve decisions
Raw data turns into KPIs, reports and views that make operational decisions easier.
Services for data-driven business processes
Commission me for a defined task or bring me into your development team. We agree on scope, priorities and acceptance criteria for your project.
Analyse and optimise SQL performance
Are slow queries holding up your work? I examine access patterns, queries and data models, identify bottlenecks and implement agreed improvements. You receive documented findings and priorities; we verify the effect using agreed measurements.
Modernise existing applications
Does a desktop application need to move to the web? I capture its existing business workflows, plan the target architecture and develop with C#/.NET, Blazor and MS SQL. The agreed deliverables include implementation, automated tests and documentation for handover.
Support your development team
Do you need experienced support for backend development, databases or interfaces? I work within your existing structures, implement agreed tasks and help with architecture, testing and deployment. Explanations, documentation and onboarding help your team continue the work.
Typical use cases
Many projects start with a simple problem: the data is there, but not where it's needed. Processes work, but with too much manual effort. Systems run, but don't talk to each other.
Replace Excel-based processes
Manual spreadsheets become structured data models, validation rules and usable web interfaces.
Make ERP data analysable
Data from existing ERP systems is unlocked for reporting, analysis and operational steering.
Build interfaces between systems
Business apps, databases and files are connected via robust import, export and API processes.
Automate recurring reports
Scheduled analyses are generated automatically from defined sources and business rules.
Prepare data migrations
Legacy data is analysed, cleansed, mapped and moved into new structures in a controlled way.
Optimise SQL queries and procedures
Slow or tangled database logic is improved, documented and made stable.
From real projects: solid solutions, not slideware
Four selected focus areas that show how datrexx approaches complex data and process landscapes – from billions of records down to AI-assisted development.
From an Oracle desktop application to a Blazor web application
In an import wholesale business, a desktop application developed and adapted over more than 20 years was to be replaced. The starting point was a VB/WinForms application with Oracle; the target was a Blazor web application with MS SQL.
I independently analysed existing components and use cases, planned and implemented the new architecture, and verified the new functions using NUnit and Selenium in a dedicated test environment. This project illustrates my approach: understand the business workflows, implement them in the new architecture and test the result.
- C# / Blazor
- Oracle → MS SQL
- Entity Framework Core
- NUnit / Selenium
Test Data Logging in semiconductor production
As technical app owner at NXP Semiconductors, I worked on TDLog, an application for checking the uniqueness of serial numbers in semiconductor production. My responsibilities included backend development, database repositories, automated tests and the CI/CD pipeline.
I coordinated requirements and architecture with the team, onboarded colleagues and supported development through deployment. I bring this experience to projects where data processing and production operations need to work together.
- MS SQL Server
- .NET Core
- Microservices
- Docker
- Redis Queue
- Azure DevOps CI/CD
Database optimisation & performance
In Microsoft SQL Server and Redis projects, I have analysed and optimised slow data access. The starting points are actual access patterns and the application’s business requirements.
For example: roughly a hundred times faster with a single index, nightly runs cut from several hours to just over an hour, blocking eliminated that only occurred in production. Cases, approach and measurement matrix →
For your project, I examine queries, data models and bottlenecks, prioritise changes and verify their effect using agreed measurements. This provides a traceable basis for deciding what to do next.
- Index strategies
- Query tuning
- Stored procedures
- Data models
- Maintainability
COMPIDDA: understand dependencies, prepare changes
With COMPIDDA, I am developing a separate tool that maps technical dependencies in established IT landscapes back to their sources. It helps identify which components could be affected by a planned change.
Analysis runs on the customer’s premises and is deterministic, without AI. Unresolved sources and mappings remain visible; business assessment stays with the responsible people. The project combines my experience in databases, process analysis and clear visualisation.
- Process analysis
- Visualisation
- Dependencies
- Knowledge transfer
- Drill-down
Pragmatic. Structured. Outcome-driven.
Good software isn't built by adding more technology. It's built on a clear understanding of processes, data and goals.
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1
Understand
First we map out processes, data sources, pain points and objectives.
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2
Structure
Requirements turn into data models, interface logic and a clear technical architecture.
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3
Build
The solution is implemented lean, maintainable and aligned with the existing environment.
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4
Test
Data, rules, edge cases and usability are checked systematically.
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5
Improve
After go-live, the solution is refined, extended and stabilised with real usage data.
Technology focused on value, not on hype
What matters isn't the latest framework but the right fit for the actual process. datrexx favours robust, understandable, long-term maintainable architectures.
Years of hands-on experience with grown system landscapes, databases, interfaces and business-critical software development.
Databases
Models, indexes, queries – clean down to the procedure.
- SQL
- MS SQL Server (SSMS, SSRS, SSIS)
- Oracle (PL/SQL)
- MySQL
- PostgreSQL
- Redis (in-memory)
- SQLite / HSQLDB
- Data Modeling
- T-SQL / PL/SQL
Integration
Connect systems without building new black boxes.
- REST APIs
- ETL
- CSV
- XML / JSON
- SFTP
- Interfaces
- Data Migration
Frontend
UIs that the people in your office actually use.
- HTML
- CSS
- JavaScript
- TypeScript
- Blazor
- ASP.NET Core
- WPF / WinForms
- Vanilla & framework-light
Backend
Stable logic that quietly does its job in the background.
- C# / .NET Core
- Java / J2EE / JSF
- Python
- PHP
- VB / VBA / PowerShell
- Entity Framework / Hibernate (ORM)
- NUnit (TDD)
- Message Queuing (Redis)
- Cron / Schedulers
Reporting & BI
KPIs that support decisions instead of replacing them.
- Reporting
- Business Intelligence
- Data Quality
- Dashboards
- Ad-hoc analysis
Ops & Tools
Comfortable in grown Linux and Windows environments.
- Linux (Ubuntu, Mint)
- Windows Server & Client
- Docker
- Git
- Azure DevOps / TFS
- IIS · NGINX · Apache · Kestrel
- Visual Studio · VS Code · Eclipse
- SCRUM · CI/CD · IoC
Tools are means to an end. The choice follows the problem – not the current trend. If something existing works well, it is integrated rather than replaced.
Manuel Hagen – software development with a feel for data, processes and real business reality.
Background
I am Manuel Hagen, a freelance software engineer with a degree in business informatics. For more than 30 years, I have worked across IT, databases and business processes. You work directly with me, from initial analysis to technical handover.
My career took me from budget controlling at PHOENIX-AG into database and application development. My part-time degree at FOM strengthened that perspective: I can discuss technical decisions with business teams and align solutions with their workflows.
At NXP Semiconductors, I worked as a Software Engineer and later FullStack Software Engineer. As technical app owner for TDLog, I helped build the backend, tests and deployment pipeline and supported architecture, planning and team onboarding.
My project experience spans semiconductor production, medical study reporting and the modernisation of business applications. This includes moving from Oracle and desktop applications to MS SQL and Blazor, and analysing existing processes and interfaces.
I work within your existing structures and share knowledge with your team. The goals are maintainable solutions, traceable decisions and a documented handover that allows you to continue the work.
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01
Understand first, then build.
Processes, data and goals are talked through cleanly before the first line of code.
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02
Simple where possible.
Complexity only where it serves the cause – not where it's fashionable.
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03
Share knowledge instead of building silos.
Architecture reviews, onboarding new colleagues, Docker and database coaching are part of the project – being a "steady rock in rough seas" for the team.
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04
Respect what's already there.
Grown systems get integrated and improved step by step, not replaced on reflex.
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05
Honest assessment.
If a standard tool is enough, I'll say so. Better no project than the wrong one.
Experience from employment and client projects
My experience includes employment at NXP Semiconductors and PHOENIX-AG, as well as freelance projects in semiconductor production, medical study reporting and business applications.
- NXP SemiconductorsFormer employer · TDLog
- ClarioMedical · former ERT
- ERTMedical · study reporting
- VeotecMedical
- Stockspiritsformer Borco
- PHOENIX-AGFormer employer · Controlling & IT
- CrematoriumWorkflow control system
Structured work
„Er arbeitet sehr strukturiert, analytisch und eigenverantwortlich …“
Excerpt from a written reference · STOCK SPIRITS
Clear communication
„… IT-Themen sowohl technisch fundiert als auch fachlich verständlich zu vermitteln.“
Excerpt from a written reference · STOCK SPIRITS
Reliability
„Herr Hagen war in ganz besonders hohem Maße zuverlässig.“
Excerpt from a written reference · NXP Semiconductors
Timely delivery
„He completed his work on time …“
Excerpt from a written reference · Clario
Short excerpts from written references, quoted in their original language. Ellipses mark omissions. Full references can be provided on request.
Why datrexx?
Database logic, interfaces and web UIs from a single source – for companies that want to leave Excel limits, system breaks and manual routines behind.
A real understanding of data and processes
Not just code, but the logic behind it: data structures, business rules and workflows are considered together.
Fits your existing IT landscape
Solutions are built where companies are today – with the systems, databases and processes already in place.
No unnecessary complexity
The architecture stays as simple as possible and as powerful as required.
Maintainable, transparent, traceable
Automation has to remain controllable. That's why clean structures, clear rules and readable code are at the centre.
Looking for an experienced freelancer for your IT project?
Tell me which application or database is involved, what needs to improve and what timeframe you have in mind. In an initial conversation, we clarify the requirements, open questions and whether my experience fits your project.