Sustainability for Java Developers: Towards an Understanding of Sustainable Java Software Development is now freely available on Leanpub, bringing together Java Champions, architects, and technical writers to look at sustainability from every angle.

The book covers everything from the environmental footprint of our data centers to the ethics of open source supply chains, from efficient data formats to the often-overlooked topic of career longevity.

The current chapters (because the book continues to grow and everyone is invited to participate) are:

• Chapter 1: Fair Trade Software — Maarten Mulders and Geertjan Wielenga
• Chapter 2: Stopping the Data Madness — Frank Delporte
• Chapter 3: Impact of Architecture — Simon Martinelli and Jan Ouwens
• Chapter 4: Career and Wellbeing — Markus Westergren
• Chapter 5: Sustaining Success: Java's Evergreen Appeal in a Rapidly Changing Tech Landscape — A N M Bazlur Rahman
• Chapter 6: Simple Things You Can Do Right Now — Jan Ouwens and Ko Turk
• Chapter 7: Java as a Scripting Language: Sustainable Code from Day One — A N M Bazlur Rahman

You'll find practical advice you can use today—like configuring build caching or using Java 25's scripting features—alongside deeper discussions about mentorship, community, and why sustainable practices actually make business sense.

The project has grown out of the Foojay (Friends of OpenJDK) community, where members from different companies and countries found they shared the same concerns about sustainability.

Because it's published on Leanpub, the book will keep evolving with reader feedback—and others are welcome to join in with their own content.

You can get your copy now at leanpub.com/sustainabilityforjavadevelopers.

The post Announcing: Sustainability for Java Developers — A New Collaborative Guide from the Foojay.io Community appeared first on foojay.

In this Foojay Podcast, we're exploring a critical topic that's becoming increasingly important in our industry: developing sustainable software that is both performant and environmentally friendly.

At the Devoxx and JFall conferences, I had fascinating conversations about how we as Java developers can make a real impact on both our cloud costs and our carbon footprint. And it's interesting to learn how these two goals are often perfectly aligned: what's good for your budget is usually good for the planet too.

We start with Daniel Witkowski. He published an article on Foojay that takes us on a deep dive into performance tuning. He explains why optimizing your code can have a thousand times more impact than saving 30% on cloud costs, and walks us through his journey of turning a simple integer validation challenge into a masterclass on Java performance optimization.

Next, I caught up with Ko Turk, who shares his passion for sustainable engineering and space exploration. He introduces us to Kepler, a tool for monitoring the energy consumption of your applications, and explains how performance optimization naturally leads to sustainability improvements.

Then Ronald Dehuysser, founder of JobRunr, reveals how his open-source job-scheduling library now enables carbon-aware job processing. He explains how JobRunr can automatically schedule non-time-critical jobs to run when renewable energy is most available.

And finally, Jan Ouwens joins us to discuss practical strategies for reducing both costs and CO2 emissions in your applications. He explains why cloud spending is actually a good proxy for your carbon footprint.

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Content

00:00 Introduction of topic and guests

02:07 Daniel Witkowski

• https://www.linkedin.com/in/danielwitkowski
• https://foojay.io/today/the-art-of-performance-tuning-why-saving-30-in-the-cloud-means-nothing-if-your-code-wastes-1000x-more/
• https://foojay.io/today/foojay-podcast-83/
• Why Saving 30% in the Cloud Means Nothing if Your Code Wastes 1000× More
• Performance tuning is less about syntax and more about craftsmanship.

29:46 Ko Turk

• https://www.linkedin.com/in/ko-turk-b271b929/
• https://github.com/sustainable-computing-io/kepler
• Sustainable engineering
• Kubernetes Efficient Power Level Exporter (Kepler)

32:46 Ronald Dehuysser

• https://www.linkedin.com/in/ronalddehuysser/
• https://www.jobrunr.io/en/
• Carbon-aware job processing with JobRunr
• Growing from an open-source project to a company

37:36 Jan Ouwens

• https://www.linkedin.com/in/janouwens/
• https://jqno.nl/
• Reducing the cost and CO2-emissions of your application
• Private cloud versus cloud providers

45:14 Outro

The post Foojay Podcast #84: Developing Performant, Cost Efficient, and Eco-friendly Code appeared first on foojay.

After this year’s success, the Voxxed Amsterdam team is proud to announce that next year will be even bigger, with more speakers, breakouts, sponsors, and attendees. We warmly invite you to join and meet us at the JUG Square on April 1–2, 2026 in Amsterdam.

Date: April 1–2, 2026
Location: Pathé Amsterdam (North)
Details & tickets: amsterdam.voxxeddays.com

Speaker Line-up

These industry leaders will be sharing their unique insights at the conference:

• Alina Yurenko – Developer Advocate for GraalVM / Open Source
• James Ward – Developer Advocate (former Kotlin Product Lead)
• Victor Rentea – Clean Coder, Java Champion, Trainer & Technical Coach
• Holly Cummins – Principal Software Engineer Quarkus
• Josh Long – Spring Developer Advocate & Java Champion
• Jeroen Egelmeers – Prompt Engineering Advocate, GenAI Whisperer, Author
• Venkat Subramaniam – Programmer, Author, Speaker, Professor

Tickets & Participation

Tickets for Voxxed Amsterdam are sold in batches. The first batch of Super Early Bird tickets will go on sale on October 8, 2026 at 09:30 CET. Please note: availability is limited (first come, first served).

📣 What’s coming up next – Get Involved!

• Call for Papers (CFP): Opening October 8 at Devoxx Belgium. Submit your talk and share your knowledge with the community! Apply here => https://vdams26.cfp.dev/#/login
• Community Reviewers: Help shape the conference program by reviewing talks and ensuring high-quality content. Apply here => https://tinyurl.com/vdams26

For Companies: Planning to buy 10+ tickets? Share this link with your manager and register via => https://tinyurl.com/Tickets-VDA-2026

The post Super Early Bird Tickets: Voxxed Days Amsterdam appeared first on foojay.