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Stephan Janssen

@stephanjanssen.be
1.3K followers 286 following 603 posts

Founder @Devoxx.com Devoxx4kids, BeJUG and DevoxxGenie | Co-founder @Voxxed.com, VoxxedDays - Founder JCS int. acquired by RealDolmen ('02) : See also @ stephanjanssen.be grokipedia.com/page/Stephan_Janssen

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Stephan Janssen @stephanjanssen.be · 1h
Wow... some amazing #Devoxx Games have arrived ❤️🤩 Deadline is tonight... game.devoxx.be
game.devoxx.be
Big personality. Little robot.
Meet Voxxy in 3D, then build a playable game with Voxxy, Droid and Biggy inside the Kinepolis Antwerp. Three winners take Devoxx Belgium tickets.
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Devoxx Belgium @devoxx.com · 3h
❤️🎙️ Devoxx Belgium Speakers on Bsky 👀
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Devoxx Belgium @devoxx.com · 4h
Speaking at Devoxx Belgium next week? 🎤 Claim your speaker profile in the Devoxx Companion app: see your ratings & feedback, upload slides, pick your photos and reply to comments. Pro tip: put your talk's QR code on your last slide ⭐ 👉 m.devoxx.com/events/dvbe26
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Stephan Janssen @stephanjanssen.be · 29/09/2026
Looks like #OpenAi is starting to connect the dots 🫣🔵🟢
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Stephan Janssen @stephanjanssen.be · 29/09/2026
Let's go!! #Devoxx redirect.devoxx.be/nl3/63Kt_x-K...
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Stephan Janssen @stephanjanssen.be · 25/09/2026
Last weekend to work on your #Devoxx Robots game! Still polishing levels, squashing bugs, or adding that one last crazy feature? Now’s the time 😅 👉 game.devoxx.be I’ll also share a short demo of my own game, just as a bit of inspiration/reference 🎮👀
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Stephan Janssen @stephanjanssen.be · 22/09/2026
#Anthropic releases Opus 5.5 👀 "30% faster than Fable but 40% cheaper than Opus 5 per task"
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Stephan Janssen @stephanjanssen.be · 20/09/2026
Parallel Constrained Decoders (PCD) as a possible solution for Agents Mis-alignment?! Love to hear your thoughts on this... www.linkedin.com/pulse/observ...
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Stephan Janssen @stephanjanssen.be · 18/09/2026
I built a native PCD (Parallel Constrained Decoder) server that embeds llama.cpp and guarantees bounded JSON. Every field gets exactly one allowed value & the probability behind it 🔥 MIT, local GGUF, macOS binary, Linux compliant 👇 github.com/stephanj/pcd...
github.com
GitHub - stephanj/pcdServer: Native Parallel Constrained Decoder Server for Apple and Linux
Native Parallel Constrained Decoder Server for Apple and Linux - stephanj/pcdServer
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Rock the JVM @rockthejvm.com · 17/09/2026
New podcast episode! Stephan Janssen (@stephanjanssen.be), creator of @devoxx.com - agentic engineering, staying ahead of the curve, and memorable conferences links below
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Stephan Janssen @stephanjanssen.be · 17/09/2026
Just released a Parallel Constrained Decoding service using java, llama.cpp with local models 🤩🔥🚀 github.com/stephanj/par... #Enjoy #Jev #LookAlike
github.com
GitHub - stephanj/parallelConstraintDecoding: Parallel Constraint Decoding using both Java and Python
Parallel Constraint Decoding using both Java and Python - stephanj/parallelConstraintDecoding
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Stephan Janssen @stephanjanssen.be · 17/09/2026
We are in the "Agentic Misbehavior" phase 🫣 #MisAlignment openai.com/index/model-...
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Stephan Janssen @stephanjanssen.be · 14/09/2026
Must see presentation on the OpenAI's Agentic attack on HuggingFace from OpenAI's engineers... 🫣 youtu.be/87DyyMV0kCY
youtu.be
Black Hat USA 2026 | The 'Breaking' News: The OpenAI–Hugging Face Incident
YouTube video by Black Hat
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Stephan Janssen @stephanjanssen.be · 08/09/2026
🤖 The #Devoxx Robot Games are ON. More info at game.devoxx.be
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Devoxx Belgium @devoxx.com · 03/09/2026
The Devoxx Belgium 2026 schedule is LIVE! 🚀 And we’re not quite done yet, expect another 10 talks to be added very soon! 🔥 Once again, the scheduling magic was powered by Timefold ❤️ m.devoxx.com/events/dvbe2...
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Devoxx Belgium @devoxx.com · 01/09/2026
34 days to Devoxx Belgium. 184 talks, 187 speakers and counting, the schedule app already open for favouriting, and two movie nights in the Kinepolis screens, including a premiere the night before it hits theatres 🍿 It's all in this week's newsletter 👇 redirect.devoxx.be/nl3/yrFcvRn8...
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Stephan Janssen @stephanjanssen.be · 27/08/2026
Replaced #Mailjet with my own self-hosted, DMARC, SPF and DKIM-compliant SMTP server. Built in just two days using spec-driven development 🔥 Another selfware project is already using it 🤩 #HavingFun
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Stephan Janssen @stephanjanssen.be · 25/08/2026
‼️Devoxx Belgium 2026 Tickets ‼️ 2nd Batch Drops August 31 at 14h00 CEST 🔥🚀 This batch will include the last available Conference-only tickets, along with a limited number of Combi and Deep Dive tickets! 👉🏽 reg.devoxx.be
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Stephan Janssen @stephanjanssen.be · 20/08/2026
90K+ downloads of @devoxxgenie.bsky.social 🎉🚀
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Stephan Janssen @stephanjanssen.be · 19/08/2026
Already 2100+ Devoxxians set to attend #Devoxx Belgium this year... Second registration batch opens on August 31st with a limited batch of conference-only tickets 🔥👀🧠 👉 reg.devoxx.be
reg.devoxx.be
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Devoxx Belgium @devoxx.com · 14/08/2026
You can already get a glimpse of what’s coming at Devoxx Belgium 2026! m.devoxx.com/events/dvbe26 🔥🚀 Updates every hour... 👀
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Stephan Janssen @stephanjanssen.be · 13/08/2026
Mailtrap wasn't working for me anymore so I asked Claude to create a local SMTP app so I can test the new #Devoxx CFP bulk email feature... #SelfWare Feel free to use it github.com/stephanj/mai...
github.com
GitHub - stephanj/mailtraxx
Contribute to stephanj/mailtraxx development by creating an account on GitHub.
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Stephan Janssen @stephanjanssen.be · 13/08/2026
Yesterday evening, during the eclipse, we held our final CFP selection meeting for #Devoxx Belgium, with both local & remote participations. A huge THANK YOU to everyone involved in reviewing and rating the talks! Expect related emails over the next two days… 🚀
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Devoxx Genie @devoxxgenie.bsky.social · 12/08/2026
See What the Agent Changed: Diffs Are Back 🔥 v1.13.0 genie.devoxx.com/blog/agent-c...
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Stephan Janssen @stephanjanssen.be · 11/08/2026
We introduced a Devoxx Belgium registration waiting room, will be interesting to see it in action next week!
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Devoxx Genie @devoxxgenie.bsky.social · 10/08/2026
V1.12.0 now supports Personas, available on the jetbrains plugin marketplace 👀 genie.devoxx.com/blog/personas
genie.devoxx.com
Personas: Switch the System Prompt Without Rewriting It | DevoxxGenie
Personas are named system prompts you pick from a dropdown in the DevoxxGenie tool window — Developer, Reviewer, Architect, Test Engineer out of the box, plus your own. Available from DevoxxGenie 1.12...
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Devoxx Belgium @devoxx.com · 30/07/2026
A new Devoxx Belgium record! 🔥🚀 We’ve never had this many Platinum Sponsors before. A huge Thank You for your trust and support. See you at Devoxx Belgium 2026!
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Stephan Janssen @stephanjanssen.be · 29/07/2026
Anybody wants to test the new Queue / Steer user prompts for DevoxxGenie? See github.com/devoxx/Devox... 👀🔥 #PreRelease
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Stephan Janssen @stephanjanssen.be · 24/07/2026
🔥 Opus 5
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Devoxx Belgium @devoxx.com · 23/07/2026
Full analysis of the 770+ received proposals for Devoxx Belgium 2026 📊👀 The program committee is now reviewing them. Meanwhile, we analysed the submission data: tracks, formats, countries, companies, and the topics speakers are bringing to the stage. blog.devoxx.be/2026/07/23/d...
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Stephan Janssen @stephanjanssen.be · 20/07/2026
This is the way: The model is The computer! taalas.com
taalas.com
Taalas | The model is The Computer
We are creating a platform that makes it easy to turn any deep learning model into custom silicon quickly.
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Devoxx Genie @devoxxgenie.bsky.social · 20/07/2026
v1.10.0 is now available on the @JetBrains Marketplace! 🚀 This release introduces preview support for Cloudflare AI Gateway models and tool blacklists, giving you more control over your AI workflows! 1) genie.devoxx.com/blog/cloudfl... 2) genie.devoxx.com/blog/run-com...
genie.devoxx.com
A Seatbelt for run_command: The Command Blacklist | DevoxxGenie
Agent Mode can now be told which shell commands it must never run unsupervised. The new command blacklist matches destructive commands like 'git reset --hard' or 'rm -rf' even when they hide inside co...
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Stephan Janssen @stephanjanssen.be · 18/07/2026
We received 166 #Devoxx Belgium proposals on the final day. Turns out the real developer superpower isn’t AI, it’s committing an abstract at 23:59 😅
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Devoxx Belgium @devoxx.com · 17/07/2026
⏰ LAST DAY to submit your talk for Devoxx Belgium 2026! Share what you’ve built, learned, solved or explored with the Devoxx community. CFP closes today at 23:59 CEST 👉 dvbe26.cfp.dev
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Stephan Janssen @stephanjanssen.be · 16/07/2026
I joke in my Agentic masterclass that we only need a simplified keyboard with GenAI, yesterday #OpenAI releases Codex mini 😅
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Devoxx Belgium @devoxx.com · 14/07/2026
Four days until the #Devoxx Belgium CFP closes. Here are the current stats 🔥🚀 👉 dvbe26.cfp.dev
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Stephan Janssen @stephanjanssen.be · 10/07/2026
Had a fantastic interactive #Agentic Engineering workshop at Faros in Leuven today. Great discussions, diverse perspectives, and plenty of thought-provoking conversations. Thanks for having me! 👊😎
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Stephan Janssen @stephanjanssen.be · 09/07/2026
What do you get when you merge MTP & MLX on Apple silicon? 🔥🍏 👀 genie.devoxx.com/blog/mtplx-l...
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Devoxx Belgium @devoxx.com · 07/07/2026
Devoxx Belgium newsletter is out 🇧🇪🤩 1) 10 Days until CFP closes! 2) Looking for Community Reviewers 👀 3) New devoxx.com/speakers champions list 👉 redirect.devoxx.be/nl3/LYFjdze6...
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Stephan Janssen @stephanjanssen.be · 03/07/2026
I had Fable 5 add this feature by looking at both the @langchain4j.dev code base and the DevoxxGenie project... awesome feature, make sure to install v1.8.12 of the plugin!🥳
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Stephan Janssen @stephanjanssen.be · 01/07/2026
What 18,000 analytic events tell us about how you use the DevoxxGenie @jetbrains.com plugin 🔥👀 genie.devoxx.com/blog/devoxxg...
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Devoxx Belgium @devoxx.com · 30/06/2026
Current status Devoxx Belgium CFP 👀 Submit your passion at dvbe26.cfp.dev 🔥
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Stephan Janssen @stephanjanssen.be · 18/06/2026
A full room of @craftsmennl.bsky.social in Friesland yesterday! We spent the day moving beyond promp(tituée) into Agentic Engineering: coding agents, skills, hooks, agent orchestrations and spec-driven development Thanks for the warm hospitality, curiosity and great discussions! 🚀
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Stephan Janssen @stephanjanssen.be · 16/06/2026
Arrived in Friesland (NL) for another Agentic Worskhop... first a swim 😅
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Stephan Janssen @stephanjanssen.be · 16/06/2026
Need some inspiration for your #Devoxx Belgium Agentic Engineering & Tooling track proposal? Here you go 👇🏽 Submit your talk: dvbe26.cfp.dev
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Stephan Janssen @stephanjanssen.be · 13/06/2026
Good thing I used #Claude Fable 5 to migrate CFP.DEV from Spring Boot 3.x → 4.x and Angular 18 → 21 !! Two days of "work" instead of weeks of upgrade pain. Test it at staging.cfp.dev 🚀
staging.cfp.dev
Call For Papers
The Call for Papers web app which allows authenticated users to submit talks and the program committee to review and rate them.
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Stephan Janssen @stephanjanssen.be · 13/06/2026
I actually predicted this in my Agentic Engineering masterclass. Europe urgently needs a CERN for AI: a coordinated frontier-model initiative to remain competitive & technologically sovereign 🇪🇺 www.anthropic.com/news/fable-m...
anthropic.com
Statement on the US government directive to suspend access to Fable 5 and Mythos 5
The US government has issued an export control directive to suspend all access to Fable 5 and Mythos 5 by any foreign national, whether inside or outside the United States.
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Stephan Janssen @stephanjanssen.be · 11/06/2026
I've been using Claude #Fable5 to significantly enhance the DevoxxGenie chat agent conversation UI and overall user experience. DevoxxGenie v1.8.2 is now live on the @jetbrains.com Marketplace. Release details below. Enjoy! 🔥
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Stephan Janssen @stephanjanssen.be · 09/06/2026
@anthropic.com Claude Fable 5 model now available 🤩🔥🤖
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Devoxx Belgium @devoxx.com · 07/06/2026
New SKILL.md lets you ask your AI assistant anything about #Devoxx & #VoxxedDays. Speakers, talks, schedules, even when CFPs are open. Works in Claude Code, Codex & Gemini CLI etc. 👉🏼 github.com/devoxx/devox...
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