Portrait of Alexander Dür

Alexander Dür

Three-time CTO, two-time co-founderSoftware and AI since 2013

Software & AI development for companies · Vienna and remote

I bring clarity to your project. And build the software for it.

You don’t need to have the technical solution figured out yet. Together we work out what you want to achieve. I keep your business in mind as well as the technology, explain the options and build the software. I work methodically and efficiently, right through to completion.

Discuss a project View projects

“No developer I know is as reliable as Alex or delivers this kind of quality.”

Sabine Niedermüller Managing Director, HeldYn

Services

What I can help you with

  1. Develop new software products

    Want to turn an idea into a product? Together we define what it needs to do. I write the specification, plan the technical approach and build the software, either as a lean minimum viable product (MVP) or as a larger application.

    Example: HeldYn · Booking platform in eight weeks

  2. Develop AI solutions and data pipelines

    Want to analyze documents automatically, generate videos or bring together data from different sources? I build software using AI and machine learning, along with data pipelines that process information and make it usable.

    Example: Reducing AI costs in a climate tech project

  3. Improve and extend existing software

    Is your software slow, unreliable or expensive to run? Do you need new features or want to modernize an older application? I get to know your system, fix the underlying problems and build on what’s there. Together we decide what to keep, improve or rebuild. I’ll also take on a migration or a complete rebuild if that makes sense.

    Example: Cutting load times by up to 90%

  4. Technical partner and fractional CTO

    Need someone who answers technical questions clearly, thinks things through with you and takes responsibility? I help you make technical decisions and choose software and vendors. If development stalls, I work with your team to clarify priorities and improve how development runs. As a fractional CTO, I take on technical leadership and write code myself when needed.

    Example: Building the product and team as CTO at PAXLY

Whether you need support with a single task or want to bring an entire project to life, let’s talk about how I can help.

You can also get in touch with individual technical questions, or for a review or an initial assessment.

Projects

Selected projects

HeldYn · Booking support for people who need care

“When Alex explains something, I understand it immediately, and I can always reach him when it really matters.”

Sabine Niedermüller Managing Director, HeldYn

Building a booking platform

HeldYn · Booking support for people who need care

Result

  • Live after eight weeks of development
  • Now a profitable company with several employees

Through HeldYn, families book support for relatives who need care. The launch called for a booking platform, search-optimized content and onboarding for caregivers. In a workshop, we decided together which features were needed for launch and which processes could stay manual for the time being. That way, the first version went live after eight weeks of development.

Read more

Goal

Through HeldYn, families book support for relatives who need care: someone to accompany them to a family celebration or the cinema, help around the house, support after surgery or physiotherapy. The aim was to turn this idea into a first usable version of a booking platform within two months.

Challenge

To launch, HeldYn needed a booking platform, search-optimized content and onboarding for caregivers, all at the same time.

My contribution

In a workshop, we defined which features were needed for launch and which processes could stay manual for now. This let the booking platform go live sooner. HeldYn already had a quote of several thousand euros for a second website to host the search-optimized content. Instead, I connected a content management system to the existing website. Now HeldYn manages all its content in one place, saves the cost of a second website and ranks higher on Google.

“When Alex explains something, I understand it immediately, and I can always reach him when it really matters.”

Sabine Niedermüller Managing Director, HeldYn

AI project

Climate tech · Finding more climate-friendly laboratory products

Result

  • 97% reduction in AI costs

The system was intended to recommend more climate-friendly alternatives to the laboratory products pharmaceutical companies were using. In the prototype, a language model reviewed every single document. With several million documents, this review would have blown the budget. So I trained a low-cost filter that passes only likely relevant documents on to the more expensive model. This cut AI costs by 97%.

Read more

Goal

The system was intended to recommend more climate-friendly alternatives to the laboratory products pharmaceutical companies were using. It needed to scale from processing a few thousand product documents to several million.

Challenge

In the prototype, a language model reviewed every document. For several million documents, this approach would have blown the budget. But for good recommendations, the system didn’t have to find every suitable product. A good selection of matching alternatives was enough.

My contribution

For training, I used documents that people had already assessed. A language model extracted the relevant passages, which I used to train a low-cost filter. Only documents it considers likely to be relevant go on to the more expensive language model.

On a separate test dataset assessed by people, the filter passed on around half of the relevant documents. That was enough for the goal of recommending suitable alternatives. AI costs fell by 97% compared with processing every document without the filter.

Improving existing software

Software for medical device approval

Result

  • Up to 90% shorter load times for core functions

The project management system helps create approval documentation for medical software. For large customers, core functions were much slower than for everyone else. I led the performance improvements and, together with a team of five developers, found and fixed the causes. Today, even large customers can work without long waits.

Read more

Goal

Users needed to be able to work with the software without long waits, even on large projects.

Challenge

The system creates approval documentation for medical software and checks it for correctness. For large customers, core functions were much slower than for everyone else. Because the software had been validated using the V-model, some changes also required us to update the documented requirements and reassess risks.

My contribution

I led the performance improvements and coordinated the work of a team of five developers. Together, we optimized algorithms, caching and database queries, among other things, and so cut load times for core functions by up to 90%.

More projects

  • AdTech · Real-time advertising auctions

    For real-time advertising auctions, I developed a model for setting minimum prices. This raised revenue by around 8% for the company and its customers, a combined gain in the millions. I also rebuilt the data pipeline so that it needs 80% less stored data.

  • Food safety · Audit data

    A system detects anomalies in audit data and explains why it flagged them. Auditors can then review the findings and use them in their decisions.

“Alex helped us implement complex parts of our system quickly and reliably. We could always count on him, and working with him was simply fun.”

Patrick Ecker Engineering Manager, AI · MedTech software

What are you planning?

Tell me briefly about it. A few sentences are enough.

Discuss a project

My companies

Co-founder twice over

As a co-founder and CTO, I’ve been responsible for products, teams and budgets myself. That’s why I also consider what technical decisions mean for your team, your users and the future of your business.

PAXLY · Packaging procurement platform

Co-founder · CTO 2016–2023

PAXLY · Packaging procurement platform

PAXLY helps companies source packaging. As CTO, I was responsible for the product and grew the team to ten employees. Software I developed to optimize packaging sizes saves leading German online retailers 10 to 15% of their packaging and shipping costs. Across two funding rounds, PAXLY received over €1 million in investment.

  • Built a team of 10
  • Over €1 million raised
  • 10–15% lower packaging and shipping costs
paxly.ai
Firmbase · Company data for the UK market

Co-founder · 2026

Firmbase · Company data for the UK market

Firmbase makes the UK company register, with five million companies, searchable by people and AI agents. Together with my co-founder, I launched the platform in 2026 and took on the technical implementation. Our customers report that the companies Firmbase finds for them are much more relevant than those they find on other platforms. A direct comparison shows this too: we ran the same customer searches on Firmbase and on comparable platforms. On Firmbase, around 80% of the results matched the search criteria; on the other platforms, about 10 to 15%.

  • 5 million companies
  • Around 80% relevant results
firmbase.co

How I work

First understand the goal, then find the fastest way to get there

  1. First conversation

    We talk about your project, your goals and your budget. If needed, you send me additional documents afterwards. The conversation is free, with no obligation.

    Result: A free quote for the next step.

  2. Clarify the goal and scope

    If it’s clear what’s needed, we can start development straight away. Otherwise, we work through the goal and the right solution in a workshop or follow-up discussions. We create a specification or mockups as needed, then I give you a quote for development.

    Result: A clear goal and an agreed scope.

  3. Deliver

    I develop the software myself or with a team and deliver in small increments. You try out new features during development. Feedback from users shows us whether the software solves their problem and feeds directly into the work that follows. For important decisions, I explain the options and their pros and cons, and give you a clear recommendation.

    Result: Software you can use while it’s still being built.

  4. Hand over

    You always have access to the latest source code and own all rights to it. At handover, I explain how the software is structured and document what matters for running and developing it further. If someone else takes over, I go through the technical details with that person or your team.

    Result: The code, all rights and the documentation. You can continue the work with me, your own team or someone else.

What matters to me

  • The right technology

    I choose the technology based on what suits your project and your team. Sometimes a ready-made solution makes more sense, such as a website builder for €20 a month. When it does, I’ll tell you, even if it means I don’t get the job.

  • Software you can rely on

    I cover all important functions with automated tests. Whenever something changes, these tests check that the software still works as intended. That way, we catch many errors early. I also automate deployment so new versions reach your users quickly and manual steps cause fewer errors.

“With Alex, nothing feels like an obstacle. Where I saw a problem, he usually already had a simple solution, and we reached our goal sooner than expected. Above all, he gives advice that fits my situation. He doesn’t recommend the same standard solution to everyone. He looks at what’s already there, what the team can do and what makes sense for your project.”

Julia Wagner Co-founder & COO, UNOMR

About

I like it when my work makes a difference.

I enjoy working with people who want to change something and are willing to put in the work. They want to bring an idea to life or finally solve a problem. If I can help, I’m in. Seeing my work make a difference for them makes me incredibly happy.

I’m drawn to challenging projects with a clear goal and plenty of energy behind them. When we tackle difficult questions together, trust each other and make decisions quickly, I’m in my element.

I enjoy working with sales teams, other founders and the people who use our software every day. Everyone notices different things. A fresh look at a problem often leads to a surprisingly simple solution. To me, truly good software is art: it works so naturally that nobody has to think about it.

Languages
GermanEnglish
Education
WU Vienna · MSc Quantitative FinanceTU Vienna · MSc Business Informatics
Location
Vienna, AustriaRemote worldwide and on-site in the Vienna area

Contact

How can I help you?

Tell me briefly about your project. You don’t need a finished specification. I read every inquiry myself and get back to you by email. In our first conversation, we’ll discuss when we can start. We agree on scope and billing before any work begins.

Currently available for new projects

  • Free first conversation
  • Code and rights stay with you
  • Scope and costs agreed upfront

Project inquiry

Tell me about your project.

What would you like to achieve, who is it for, and where do things stand? A few sentences are enough.

I use your details to handle your inquiry. Details in the privacy notice. * Required field

Prefer to talk first?

Book a call

Or email me at office@alexduer.com.