Marcus Hellberg

Applied AI Researcher, Speaker, DevRel expert.
Java Champion.
VP of AI Research @vaadin

[Marcus Hellberg @marcushellberg]

Oh wow, what an honor 🤩 The Java community is amazing

[Java Champions @Java_Champions]

Congratulations to new #Java Champion @marcushellberg

[Vaadin @vaadin]

Where does full-stack Java go next?

Vaadin Create 2026, Barcelona, Oct 27–28: 2 days, 3 tracks, 20+ speakers including Josh Long.

Trailer: https://t.co/4ROfAmCM52
Tickets: https://t.co/obRvD1jKe9

[Simon Martinelli @simas_ch]

Vaadin is AI native. And it's an amazing fit for Spec-Driven Development.

Vaadin 25.3 is built for AI coding agents that work on Java UIs:

✅ A dev loop that works like an IDE for your agent

✅ A self-hosted MCP server with the full Java API (even air-gapped)

✅ Browserless tests, so the agent gets fast feedback without a browser

✅ An Observability Kit insights endpoint your agent can read

Why does this matter for Spec-Driven Development?

With Vaadin, the UI is plain Java. No JavaScript, no REST layer, no second tech stack. The agent works in one language and one codebase. That makes it much easier to go from the spec to running code, and to check with tests that the code still matches the spec.

Specs give the direction. Vaadin keeps the path short.

🎥 Watch the 5-minute overview: https://t.co/eWFKieyC9Z

📣 Want to see it live? Next week I speak at Vaadin Create 2026 in Barcelona (27-28 October): "Spec-Driven Development - Why Vaadin Is the Perfect Fit"

AI can generate code. The hard part is to keep it aligned with the system you really want to build. I will show how specifications and architectural guardrails guide a full-stack Java application while it grows.

See you in Barcelona! 🇪🇸

https://t.co/oaAZIhKkqj

#Vaadin #Java #SpecDrivenDevelopment #AIUP #AI #VaadinCreate

[Marcus Hellberg @marcushellberg]

Vaadin 25.3 shipped a ton of improvements for AI development, new components, and improved production observability. Check out the highlights!
https://t.co/z4pACQ8vnr

[Marcus Hellberg @marcushellberg]

@therealdanvega You could arrange a Vega family conference called Las Vegas 😂

[Marcus Hellberg @marcushellberg]

Vaadin 25.3 improves the AI dev loop 🤖

🧠 MCP, skills & agent tools give coding agents up-to-date Vaadin context
⚡ Browserless tests let agents self-verify changes in milliseconds
🎨 Dev Loop makes UI tweaks visible instantly

https://t.co/LcavEKULb6

[Simon Martinelli @simas_ch]

How fast can your AI agent find out that the code it just wrote is correct?

This question matters more than ever. Agents write code in seconds, but browser-based tests take minutes and often fail for the wrong reasons: timing, waits, flaky selectors.

Vaadin Browserless Testing changes this. The whole flow runs in one JVM: the view, the validation, the service, the jOOQ query. Tests run in milliseconds and are deterministic. When a test fails, the code is wrong. Not the timing, not the network.

Bonus: JaCoCo sees the UI code too, so you get one honest coverage number for the entire application.

In my new blog post I explain why this is a game changer for AI generated web applications, and why the classic SPA architecture cannot match it:
https://t.co/dDa3nJVp7Z

#Vaadin #Java #SpringBoot #jOOQ #Testing #AI

[Marcus Hellberg @marcushellberg]

Welcome @Sharat_Chander 🥳

[Java Champions @Java_Champions]

On behalf of the @Java DevRel Team at @Oracle, congratulations to the newest member of the #Java Champions Program @Sharat_Chander

[Marcus Hellberg @marcushellberg]

@alejandro_du @FellowProducts @claudeai Indeed 🤓

[Marcus Hellberg @marcushellberg]

Problem: I have a very nerdy @FellowProducts coffee maker and grinder that lets me configure all the things.

Solution: have @claudeai create a tool to determine starting values for grind size based on the beans and brew batch size 🤓

[Marcus Hellberg @marcushellberg]

@slava_imeshev Sorry, I realize the way I put that might have been misleading. What I meant is that we are not planning to deprecate Lumo. Whenever we’ve shipped a new theme, we’ve always kept the prevous one around for a good while to avoid people having to migrate their themes unnecessarily.

[Marcus Hellberg @marcushellberg]

This is cool! There's now a Vaadin Aura theme preset gallery and theme builder: https://t.co/FZ4QdlPNJX 🎉

The functionality will also be available in Vaadin Copilot shortly!

[Marcus Hellberg @marcushellberg]

@slava_imeshev What are the things that make you want to stay on Lumo? The look and feel? The amount of customization you've built on top of it?

We don't have plans on deprecating Lumo right now, I'm just interested in learning what you feel is better in Lumo than in Aura to help us improve it

[Marcus Hellberg @marcushellberg]

@jonas_toma We don’t have any plans of deprecating it as of yet. We’ve eventually deprecated older themes in the past, so it’s likely to happen at some point in the future, but not in the near future.

[Simon Martinelli @simas_ch]

A small experiment with Claude Code:
Hotel room search, built twice.

1) Vaadin + Spring Boot + jOOQ + Testcontainers + PostgreSQL: 3 minutes.
2) Angular + Python + DynamoDB: about 5x longer.

Why the gap? One stack is one language, one runtime, and a clear data model. The other is two ecosystems, two languages, and design decisions that need to be made up front.

Choose your tech stack wisely.

[Vaadin @vaadin]

Vaadin 25.1 brings reactive state management to Java—define your state once, and your UI stays in sync automatically.

#Java #FullStack #WebDev #ReactiveProgramming

[Marcus Hellberg @marcushellberg]

Vaadin 25.1 is out. Despite it's minor version bump, it comes loaded with some big features 🤩 Want to learn more and ask the team questions? Join our live stream in 15 minutes: https://t.co/1Ay3iSAWWw

[Marcus Hellberg @marcushellberg]

@Sharat_Chander @vilojona @Oracle So sorry to hear that Shar, a big loss for the Java community. Wishing you the best of luck on finding your next adventure.

[Marcus Hellberg @marcushellberg]

Cool side-benefit of using signals for state management in Vaadin: state is persisted across code hot swaps 🤩 (even scroll position is preserved!)

[Marcus Hellberg @marcushellberg]

@kristoftaveirne Awesome! Glad to hear that 👏

[Marcus Hellberg @marcushellberg]

Vaadin 25.1 is out! 🥳

Signals for reactive UI state management is the biggest update to our Java API since Vaadin 10 (but this time without breaking changes)!

Other goodies:
🧑‍✈️ Copilot is free
🧪 Browserless UI testing is now free
🤖 New AI chat components

https://t.co/QBspNwQlWb