iiinova — where your digital self keeps evolving

Markus Harrer @markusharrer.de · 15/09/2026

Will AI wipe out humankind? However unlikely it may be, I'm prepared for the Terminator scenario. I always keep a piece of old legacy code with me.

000

Markus Harrer @markusharrer.de · 26/04/2026

Current status: Discussing with an LLM the impact of Karl Popper's Three Worlds Theory on agentic software modernization. Yes, it's as absurd as it sounds. Bonus content: Gemini 3 Pro's statement when asked why it is so absurd attached (at least we "agree" on this).

000

Markus Harrer @markusharrer.de · 27/03/2026

I still don't get for what I should use OpenClaw.

120

Markus Harrer @markusharrer.de · 21/02/2026

I've been working in the intersection of AI, Data Science and Legacy Modernization for over a decade now. Now it's time to take it even further with LLMs to make AI-assisted Software Evolution work to tackle legacy software modernization (and have fun playing around with new toys at the same time ☺️)

212

Markus Harrer @markusharrer.de · 19/02/2026

Now updated with new colors and without misleading numbers.

000

Markus Harrer @markusharrer.de · 19/02/2026

I don't build AI into legacy systems. I use AI engineering for building analysis and modernization tools on greenfield using Python/pandas/Neo4j/OpenRewrite for analyzing legacy systems.

011

Markus Harrer @markusharrer.de · 18/02/2026

Why does working with AI agents in legacy systems feel so much harder than in all those vibe coding demos on YouTube? 🤔 Part of the answer: 😊 Popular language + Greenfield ☘️ = "AI heaven" 😯 Niche language + Brownfield 🟫 = "AI hell" More about this topic: markusharrer.de/blog/2026/02...

385

Markus Harrer @markusharrer.de · 11/02/2026

The picture looks different for 754 Java files, 8711 methods, and 82830 SLOCs. But there are still method clusters (that don't fit the package structure at first glance).

010

Markus Harrer @markusharrer.de · 11/02/2026

Here I demo how you can use machine learning techniques to visualize your legacy code on another abstraction layers with "method clusters": Left: structural similarity Right: functional / business purpose (via LLM) Colors: The real domain-oriented modules More: github.com/feststelltas...

131

Markus Harrer @markusharrer.de · 27/01/2026

It's not just "Human 🧒 vs. AI 🤖" these days when you're thinking about transforming legacy code on a larger scale. That is why I visualized a part of the refactoring tools landscape using my favorite thinking tool: PowerPoint 🧡

022

Markus Harrer @markusharrer.de · 30/07/2025

I've collected and structured some software modernization strategies in an overview: feststelltaste.github.io/littlestmode...

020

Markus Harrer @markusharrer.de · 23/06/2025

"To AI or not to AI", that is the question. This is why I've created a one-page guide that helps you make decisions on when and how to use AI for software modernization. PDF: speakerdeck.com/feststelltas... #legacy #ai #modernization

042

Markus Harrer @markusharrer.de · 08/04/2025

I'm working on a new hands-on version of my software architecture improvement training (iSAQB IMPROVE) using good old Fischertechnik (hey, it's about a legacy system, okay?). Here you can see a feature toggle in action. 😬

040

Markus Harrer @markusharrer.de · 07/04/2025

To find your inner peace using vibe coding as a programmer, you absolutely have to make sure you put that in the very first line of your generated scripts 😄: # vibe coded

The first lines of a Python script where the first line is "# vibe coded"

011

Markus Harrer @markusharrer.de · 22/03/2025

Just a quick demo, nothing fancy: Importing CodeCharta files into Pandas, visualizing / adding some stuff and export it again to visualize also the new stuff in CodeCharta Web Studio: nbviewer.org/github/fests...

032

Markus Harrer @markusharrer.de · 21/03/2025

How is your morning going? My source code analysis tool just crashed because of too many source code files 🤪 #softwarearchaeology

000

Markus Harrer @markusharrer.de · 14/03/2025

Meet me at @amaconf.bsky.social April 3 - 4, 2025 in Berlin. I'll be speaking about how Wardley Mapping can help software architects avoid both overengineering and underengineering software quality. I'm also talking about why building in quality into software systems becomes harder over time.

Quality is all about the How, not the What.

011

Markus Harrer @markusharrer.de · 13/03/2025

Back then, I hadn’t thought something like this would ever happen - until today: Claude Code also knows my work on data-driven software analysis of software systems and can now write similar scripts to gain a deeper understanding of software systems and their evolution. This is really 🤯

000

Markus Harrer @markusharrer.de · 13/03/2025

Great that Claude Code knows all my Software Analytics Jupyter Notebooks on GitHub. That's very handy now 🤣

000

Markus Harrer @markusharrer.de · 03/12/2024

Me: The handle on the toaster is broken. I need a 3D printer for printing out a replacement part! My wife:

The toaster handle fixed by a clip from IKEA for closing plastic bags.

040

Markus Harrer @markusharrer.de · 03/12/2024

These are my most-starred GitHub repositories. Not so bad for such niche topics, I guess. 😊 Links and more here: star-history.com#feststelltas...

010

Markus Harrer @markusharrer.de · 03/12/2024

I don't understand why someone should use anything like the C4 model. The agile manifesto clearly states that you should not use tools, plans and documentation at all!!11!1eleven!1!11! /s

250

Markus Harrer @markusharrer.de · 27/11/2024

Hello new followers! Welcome! I'm primarily writing about all the things that could make the lives of developers working on legacy systems more enjoyable 😊. (And thanks for the nostalgic Twitter vibes from earlier times! 😃)

An image from the movie Avengers: Endgame showing Captain America leading a group of heroes into battle, with the text 'FORMER TECH TWITTERERS ASSEMBLE'.

020

Markus Harrer @markusharrer.de · 18/11/2024

Naming things is one of the hardest problems in software development 🤯. Beyond creativity challenges, synonymy (many names for one thing) and polysemy (one name, many meanings) can easily confuse developers 😖. The fix? Ensure integrity with consistent, clear concepts throughout your codebase. 💡

The image contrasts natural language issues with best practices in code. On the left, it shows problems in natural language: synonymy (one thing, many names like DataAccess, Repository, EntityHandler) and polysemy/homonymy (one name, many things like Client, Order, Entity). On the right, it illustrates the solution in code: integrity through consistent naming, where one thing maps to one clear concept, such as Customer, procurement.Order, and data.*Entity. The image emphasizes the importance of conceptual integrity in software architecture to prevent confusion.

020

Markus Harrer @markusharrer.de · 15/11/2024

Yes, but that's what the documentation said!

000

Markus Harrer @markusharrer.de · 06/11/2024

Fixed this slide 😅 (und danke für den Einblick hinter die text2cypher Kulissen)

120

Markus Harrer @markusharrer.de · 06/11/2024

I've created a new Twitter banner. Feel free to use and change as you like: gist.githubusercontent.com/feststelltas...

000

Markus Harrer @markusharrer.de · 05/11/2024

I think a new era of Software Analytics is emerging, where we can not only analyze software systems in a context-specific way to find appropriate solutions but also improve software systems through data-driven approaches,too. Interesting times 😊

010

Markus Harrer @markusharrer.de · 05/11/2024

Oh, I found that slide again! 😄 It's about whether AI is a threat to Software Analytics in the sense that analyzing software systems might become unnecessary because AI could 'automagically' fix all problems. My answer: as long as LLMs write code like humans, we're safe. 😅

010

Markus Harrer @markusharrer.de · 05/11/2024

yeah, and that at a GOTO conference 😂

020

Markus Harrer @markusharrer.de · 05/11/2024

Found that quote in my master thesis again. I still like that one 😄: "In God we trust. All others must bring data." -- William Edwards Deming

010

Markus Harrer @markusharrer.de · 22/07/2024

🚀 Exciting news! My new book "Quality Tactics" is now available on @leanpub.bsky.social! Dive into a variety of strategies to improve the quality of software systems, their development and operation! Get your copy today! 🏅 📘 leanpub.com/qualitytactics #QualityTactics #SoftwareArchitecture

An image of a book titled "Quality Tactics: Develop Quality-Driven Solution Strategies for Software Architectures" by Markus Harrer. The cover features illustrations of people interacting with various icons representing different quality tactics. The image also showcases various strategy cards like "Fake Progress Bar," "Parallelization," "Data Quality Checks," and "Microservices" with descriptions. A banner reads "Systematically find solutions aligned with quality goals," and there is a note about early access and PDF flashcards availability at https://leanpub.com/qualitytactics.

051