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The longest day of the year is comming and let's another Kotlin meetup. This time we geather at N26! **⚠️⚠️⚠️ Due to a venue policy please submit the following form for additional details. Without it, you won't be allowed inside the venue:** https://forms.gle/XjqVXkD3FARCM6jA8 **Line-Up:** 👉 **TestBalloon: Kotlin testing is easier (and more fun) than you think** *by Oliver Okrongli* You want an easier way to write tests? Parameterize tests in plain Kotlin? Reuse a series of tests? Easily extend own your test setup? Have first-class support on all platforms? All without struggling with a huge framework API? TestBalloon is a new test framework that brings the power of Kotlin to your test setup. With a small-surface API, a hierarchical test structure and an extensible DSL, TestBalloon makes Kotlin testing easy, even at scale. Oliver, the author of TestBalloon, will show testing patterns and strategies and lots of practical examples, ranging from simple unit tests with less boilerplate to advanced testing with coroutines and generated data. This talk is based on insights first presented at KotlinConf 2026 in Munich. At the end of this talk, you’ll be able to firmly the answer the question: "How can I master Kotlin testing with ease, and make my team release with joy and confidence, every time?" 👉 **One Topic to Rule 'Em All** *by Yonatan Karp-Rudin* Kafka delivered every event exactly once, in order, and lost nothing. So what broke? This talk follows that question into the gap most event-driven systems leave open: what actually guarantees the order your domain depends on, and what quietly doesn't. We start from a real log line, find the crack in an architecture that looks clean and ships fast, and rule out the fix everyone reaches for first. The cure turns out to be one sentence of domain thinking plus one line of config, though the Schema Registry will fight you on the way there. A live demo runs the bug and the fix back to back: same load, same hero, one change. If you build with Kafka, you have probably shipped a version of this bug. You will leave able to spot it and fix it before it pages someone. 👉 **TBD** **Speaker Bios:** 🗣 Oliver Okrongli Oliver has been shaping and creating software from backend to frontends. He is the author of TestBalloon, a next-generation Kotlin test framework. Before, he has helped to maintain Kotest, and contributed to several libraries of the Kotlin ecosystem as well as the Kotlin compiler. Can be found on GitHub (OliverO2) and the kotlinlang Slack (Oliver O). When not developing, he is most probably in deep talks, dancing, snowboarding or F18 catamaran sailing whenever he gets a chance. 🗣 Yonatan Karp-Rudin Yonatan Karp-Rudin is a Staff Engineer at Billie, building event-driven systems in Kotlin and Spring Boot. Off the clock, he plays with AI agents and builds random tooling, trying to hand off as much of his own workflow to a machine as he can. The rest of the time he's brewing mead or deep in a video game. **🗣 TBD**

We are happy to invite you to our next iOS meetup. This time we cooperate with the amazing 42 Berlin to share the knowledge and experience in iOS development. 18:00 Doors open 18:30 Welcome on campus **18:45** **— Sebastian Hagedorn, director of Engineering at Clue, presents "The Sensitive App".** Is your app really working, or just not crashing? “The Sensitive App” reports subtle bugs regardless of origin, and validates your assumptions in production so you don’t have to resort to guessing or praying. Learn how to turn your app into the first line of defense for your entire system’s health! **19:45** **— Dmitry Kurkin, lead Mobile Engineer at SuperNext, presents "Lessons that iOS Native Project could learn from ReactNative in agentic development".** We'll inspect the components of the React Native engine that provide faster feedback and boost agentic iterations.

Join us for the first meetup 100% dedicated to agentic analytics in Berlin. **The goal:** share real-world feedback between data teams on implementing analytics agents. **The format:** a roundtable with 4 data teams who have tested or deployed analytics agents using different solutions - Cortex, Dust, Hex, nao, Omni, Looker, or in-house tools. **[RSVP on Luma.](https://luma.com/ly17mjtj)** 📣 **Speakers of the night:** * [Marina Ariamnova](https://www.linkedin.com/in/marina-ariamnova/?utm_source=luma), Analytics Manager at SumUp - LangChain vs Dust * [Andrey Pushvintsev](https://www.linkedin.com/in/pushvintsev/?utm_source=luma), Staff Analyst at Miro - Claude + custom BI MCP * [Marielle Dado](https://www.linkedin.com/in/marielledado/?utm_source=luma), Senior Analytics Engineer at CarOnSale - Dataleap, Langdock, Claude + Snowflake Cortex MCP vs Secoda AI * [Andre Wagner](https://www.linkedin.com/in/andre-wagner/?utm_source=luma), Director of Data Analytics at Taxfix - Claude + custom plugin vs Looker The panel will be moderated by [Christophe Blefari](https://www.linkedin.com/in/christopheblefari/?utm_source=luma), founder of [nao Labs](https://getnao.io/?utm_source=luma). **Agenda** 6:30 PM: Doors open 7:00-8:00 PM: Roundtable 8:00-10:00 PM: Drinks and Networking **About our sponsor:** [nao Labs](https://getnao.io/?utm_source=luma) helps teams build and operate AI coworkers for analytics and operations. Their platform focuses on practical, production-ready agent workflows so companies can turn LLM capabilities into measurable business outcomes. **About our host:** [Trawa](https://trawa.energy/?utm_source=luma) is a Berlin-based energy platform helping businesses access cleaner and more cost-efficient electricity. By combining software, data, and energy market expertise, trawa enables companies to optimize procurement and better manage energy costs. Want updates or more info? Subscribe to our newsletter: [databerlin.substack.com](https://databerlin.substack.com) Follow us on LinkedIn: [Data Berlin on LinkedIn](https://www.linkedin.com/company/data-berlin/?utm_source=luma) Looking for a job? [databerlin.net/jobs](https://databerlin.net/jobs) Join our Slack community: [Data Berlin Slack](https://join.slack.com/t/databerlin/shared_invite/zt-2q6j9x0z8-~sG7o3Q8S2j4j5gXg2yHlw)

Today we are working at Moxy Ostbahnhof, a beautiful air conditioned location near Ostbahnhof with big desks, booths and available food/drinks. **Cost:** There is no payment required, but it is common courtesy to buy drinks or something from the people providing the space. If you want to chit chat with out coworkers, please check out our Telegram channel: **[https://spam-destroyer.com/check/jelly](https://spam-destroyer.com/check/jelly)** 😴 Tired of working by yourself? 🌡️ Too hot to work at home? 🍫 Do the contents of your fridge, or housework, distract you while working from home? 💻 Come join other freelancers and remote workers for coworking! ☕️ There are no membership requirements, free WiFi, some power sockets, a large desk, some affordable coffee, toasted sandwiches and drinks! ⏰ We'll be there from 11:00, but feel free to stop by any time. The venue is open in the morning too. • DO WE HAVE PERMISSION? • Yes, we have permission to use the hotel as a coworking spot. So long as we are paying customers, they are happy for us to use their location for coworking between the hours of 11:00 to 17:00. They're sometimes (but not always) quite busy and short on tables and chairs outside of those hours. • WHAT TO BRING • Whatever you need to work on your own project / tasks :) • QUESTIONS? • Join our Telegram chat group to ask any questions: [https://spam-destroyer.com/check/jelly](https://spam-destroyer.com/check/jelly) • MORE EVENTS? • To have more events, we need more organisers. If you would like to help out, please get in touch [😀](https://emojipedia.org/grinning-face/)

🌟 Join us for **"Don't Eat Alone"** – an event designed to transform your lunch break into a social feast! **Tired of solitary meals in front of the computer?** **Thriving to meet some new people and curious what it may bring to your life?** Just come, check and enjoy a delicious meal with friendly faces. Connect with like-minded individuals, engage in conversations, and make your lunchtime a memorable social experience. Mark your calendar, bring your appetite, and let's build connections, one meal at a time! 🍽️🤝✨ PAYMENTS: the meetup is free, but everyone pays for their meals. Here you can pay by card easily.

Deadline Table — Focused Work Hours Bring your manuscript, your taxes, your laptop—whatever needs to get done. We have WiFi and phone sockets. You’ll sit on bar stools at the counter (not comfortable, by design). Two hours to focus hard. We’ll keep you accountable so you actually finish. Choose your intensity level: Level 1 — Light Touch: We check in once at the start, once at the end. You’re on your own. Level 2 — Mild: We check every 15 minutes. Gentle nudges if you drift. Level 3 — Strict: We’re watching. Phone down? We see it. Daydreaming? We call it out. Sign on your table says: “Stop procrastinating.” Two hours for €7.50 minimum order. If you need more time, it’s €3.20/hour after. Five seats, first come first served. No distractions. No bullshit. Just work that gets done. 100% plant-based. Inspired by Tokyo manuscript cafés. Hours: Wed–Thu: 1 PM–10 PM Fri: 4 PM–10 PM Sat–Sun: 12 PM–10 PM Closed Mon–Tue

## A space where creativity flows, conversations open & ideas come to life. Relax after work and step into a chill, social atmosphere designed for drawing, painting & connecting. Whether You know it as *Drink & Draw*, *Sip & Paint*, or *Wine & Paint*, this experience brings together the best of art, people & good energy — all in one place. Our sessions are perfect for all levels — whether You’re picking up a brush for the first time or already feel at home in art. With easy and encouraging guidance from our Creative Teachers, You’ll create Your own artwork using pencils, acrylic paints and/or oil pastels, while enjoying a laid-back & inspiring environment. Whether You’re coming with colleagues, meeting friends, planning a date, or simply taking a moment for Yourself after a long day — this is Your space to relax, connect &express Your creativity. ‍ > Each session offers a new theme, fresh inspiration &the chance to take home something You created Yourself. ‍ ##### **INCLUDES:** **‍**All Materials (canvas, pencils, acrylic paints, oil pastels, brushes & more) + 2 glasses of wine / cocktail (2 × 200 ml) or 2 Soft Drinks & Water ‍ ##### **SIGN UP & TICKETS:** **‍**No registration needed. Simply come by & get Your ticket at the box office before the class. ‍ LEVEL: All levels WHAT YOU NEED: All materials provided (canvas, acrylic paints, oil pastels, brushes & more) COSTS€28 General \| €5 for DNA\. Members See You Soon :) Love. DNA.

The Creative Code Jam is a monthly gathering of artists, makers, designers, illustrators, coders, musicians, performers, learners and anyone interested in the use of computing skills for artistic expression. The event is free and open to all, regardless of age, origin, gender or experience. The jam is an opportunity to meet likeminded people and get creative together in a relaxed and safe environment. Beginners and first-timers should feel especially welcome! WHAT SHOULD I EXPECT? **Bring a laptop** and/or anything you’d like to work on, whether it’s a personal project, an experiment, or a skill you want to learn. You can come with friends or meet new people here. There’s no set agenda: some people code, some sketch ideas, some collaborate, and others just chat and get inspired. SCHEDULE Doors open at noon, then we’ll have quick introductions so everyone can share what they’re planning to work on. Note: arriving on time is the best way to hear what others are up to ;) Around 6 pm, we gather to share what we’ve worked on during the day. BEGINNERS WELCOME! If you’re new to creative coding, we'll be happy to help you get started, and you can find beginner-friendly resources at [creativecode.berlin/learn](http://creativecode.berlin/learn). THIS IS YOUR SPACE We do our best to create a welcoming environment for all people regardless of race, ethnicity, color, religion, gender identity, sexual orientation, national origin, age, disability, or genetics. People from group generally underrepresented in open-source, art, and technology fields are warmly encouraged to come by. And if you know someone who might enjoy this meetup but isn’t sure it’s for them, let them know they’ll be welcome! SAFE SPACE POLICY We support the Berlin Code of Conduct: https://berlincodeofconduct.org/ Please make sure you agree with its content. ABOUT MotionLab.Berlin MotionLab.Berlin is Germany’s premier Innovation Hub & Makerspace – an ecosystem for Hardtech, art, creativity, and entrepreneurship. They are an international community with access to state-of-the-art machinery, prototyping machines, coworking spaces, offices, and production facilities. More info: https://motionlab.berlin/ ACCESSIBILITY MotionLab is located on the ground floor, with bathrooms on that same level, although unfortunately they are too small for wheelchairs. FOOD MotionLab has drinks and snacks for sale. Bio food can be found on LPG at Bouchéstr (\~200m). Their cantine has vegan, vegetarian and other food options until 8pm. DO I NEED TO SPEAK GERMAN? We speak mostly English so international guests are more than welcome! Our team also speaks French, Turkish, Italian, Spanish, Dutch, Finnish and German... though language availability may vary depending on which organizers are present :) CONTACT Raphaël de Courville team@creativecode.berlin +49 176 700 70572 or get in touch via [creativecode.berlin](https://creativecode.berlin/)

Unser Verein berlinCreators e.V. trifft sich jeden Freitag ab 18 Uhr im Makerspace. Wir haben Gruppen rund um Elektronik, 3D-Druck, Nähen, Programmieren, Retro Computer. Egal ob Anfänger oder Profi – hier seid Ihr Willkommen. Ihr könnt mit anderen fachsimpeln, Euch inspirieren lassen oder auch mit unserer Hilfe Eure ersten Projekte starten. Wenn Ihr Euch bei uns wohlfühlt und Mitglieder bei den berlinCreators werden möchtest, freuen wir uns. Kommt vorbei, lernt den Space, uns und die Möglichkeiten kennen.

Hallo zusammen! In Rahmen der PAKD Gallery Kurse bieten wir euch einen Zeichenkurs an. Wenn Ihr Zeichnen liebt und eure Fähigkeiten weiterentwickeln möchtet, dann seid Ihr hier genau richtig. In diesem Video erzähle ich euch von meinem Kurs für realistisches Zeichnen mit Bleistift - und wie er Eure künstlerische Arbeit auf ein neues Level bringen kann. Hattest Du schon immer das Gefühl, zeichnen können zu wollen - Dir fehlt aber die richtige Anleitung? In diesem Kurs lernst Du realistisches Zeichnen mit Bleistift, einfach, verständlich und Schritt für Schritt: • Korrekte Perspektive • Licht und Schatten • Materialdarstellung wie Glas, Keramik, Stoff, Metall Der Kurs ist perfekt für Anfänger und für alle, die ihre Fähigkeiten verbessern möchten. Wenn dieses Video Eure Leidenschaft für das Zeichnen mit Bleistift geweckt hat, dann schickt mir einfach eine E-Mail und lasst uns gemeinsam eure Reise in die Welt des realistischen Zeichnens mit Bleistift beginnen. Kleiner Kurs, große Wirkung. Maximal 12 Teilnehmer\*innen! Anmeldung: kifan@pakd-gallery.com Sichere dir deinen Platz, bevor alles ausgebucht ist. Samstag 11:00 - 14:00 Uhr. 25€ für eine einzelne 3- stündige Einheit 200€ für ein 10er-Paket, flexibles einlösbar.

At OpenSpace Networthing entrepreneurs from diverse disciplines, industries and nations meet to collaboratively develop solutions for challenges presented by participants. This month we will dive deeper into building digital products with Vibe Coding & AI with Varun Jain. We are building a networking-App: The "Tinder for Entrepreneurs" If you want to offer a workshop or present a topic for our members, write an email to alejandro.wagner@mlp.de Entrance is free! Bring in your expertise instead.

Das alte T-Shirt mit einem Statement-Print wiederbeleben, eine verlorene Spielfigur nachdrucken oder einen Stempel designen: MeetUp im Humboldt Forum! In diesem dreistündigen Workshop sind alle Interessierten mit und ohne Vorkenntnisse dazu eingeladen, verschiedene Maker Space Technologien kennenzulernen. Wir erklären an unterschiedlichen Terminen (s.u.), wie sich mit Laser Cutter, 3D-Drucker, Schneidplotter, Näh- oder Stickmaschine nützliche Dinge für den Alltag herstellen lassen. Inspiriert von den aktuellen Ausstellungen und Themen des Hauses, können am Laptop mit der Software Inkscape oder Tinkercad eigene Grafiken und Objekte entworfen und gestaltet werden. Wer sich geschickt anstellt, kann am Ende ein fertiges Produkt mit nach Hause nehmen. Die Personenzahl ist begrenzt. Bitte buchen Sie **am Veranstaltungstag an der Tageskasse im Foyer** pro Person ein kostenfreies Teilnahmeticket! Der Workshop ist nicht für Kinder und Jugendliche unter 16 Jahren geeignet. **Die nächsten Termine und Themen:** **Nützliches aus Filz mit der Stickmaschine** 25\. April \(ohne/geringe Vorkenntnisse\) und 2\. Mai \(Fortgeschrittene\) **Pins und Anstecker aus dem 3D-Drucker** 23\. Mai \(ohne/geringe Vorkenntnisse\) und 30\. Mai \(Fortgeschrittene\) **WM-Special: Fan-Trikots selbst gemacht – Bitte T-Shirt mitbringen!** 20\. Juni \(ohne/geringe Vorkenntnisse\) und 27\. Juni \(Fortgeschrittene\) **Weitere Informationen:** Kostenfrei. Bitte buchen Sie Ihr Ticket direkt am Veranstaltungstag an der Tageskasse im Foyer. **Die Ticketbuchung im Voraus und im Webshop ist nicht möglich.** Dauer: 180 min. Ab 16 Jahre. Sprache: Deutsch, Englisch. Rollstuhlgerecht. Ort: Werkräume, 1. OG. Maximal 15 Personen.

**3 Teams, 3 Hours, 3 Songs** 🔴 ⏯️ Find your next collaborators and learn how to make a song together in one day. **Exclusively for FLINTA\*** **(only for Women, Lesbians, Nonbinary-, Trans-, Agender People).** Join us: **Saturday, June 20** **15:30-18:30** **House of Music (343 Labs, 2nd floor)** **What to expect:** Up to **12 people** gather in **3 teams** working on a song together. This guided songwriting sprint will give you the opportunity to exchange ideas and **get creative**. At the end there will be 3 songs and a lot of new connections. As a challenge, everyone brings a field recording of that day to be incorporated into the songs. This can be the sound of your coffee machine, the noise of a subway passing by or your baby crying, bring what moved you on that day. Together we will exchange the sounds and see what the 3 teams create out of it. **What you need to bring:** \- Laptop with your favorite DAW \- Ableton Live\, Logic Pro\, etc\. **(!)** \- a field recording from that day on your phone/flash drive/etc\. \- openness to expirement in a team of people you have not worked with before \- extra gear if you want to **Speakers and midi keyboards provided for 3 teams.**

Welcome to Sunday Tech Coffee. This is a **networking** event for those in the tech industry in Berlin. We are usually inside and to the right. Ask the barista/bartender if you can't find us.

Come chat about Atlassian tools and best practices at the Reynoldsburg Sunny Street Cafe and Breakfast is on Atlassian! Let's get the day started off with breakfast with your ACE Leaders! We're always excited to talk about Atlassian Products, share our knowledge and hand out swag! Come chat with us about new product news and anything you are working on within the Atlassian product stack. This is a great opportunity to come see what we are all about, hear new business news and share with other Atlassian users your questions and experiences. We'd love to see new and old friends come out to chat and learn about Atlassian! Agenda --- Moderators Kimberly Deal - Columbus Atlassian User Group Leader Kevin Stanley - Columbus Atlassian User Group Leader Greg Sprowls - Columbus Atlassian Community Leader Hosted By Kimberly Deal, Atlassian User Group Leader Kevin Stanley, Chief Everything Greg Sprowls, Agility Lead --- Global Partner Atlassian (http://atlassian.com) Millions of users globally rely on Atlassian products every day for improving software development, project management, collaboration, and code quality. Partner Atlassian --- For over a decade, Atlassian customers have come together to network, share ideas, solve problems, and find new ways to use Atlassian products. Today, more than 15,000 people take part in Atlassian community events in more than 30 countries. --- Complete your event RSVP here: https://ace.atlassian.com/events/details/atlassian-columbus-presents-rise-and-shine-with-atlassian-reynoldsburg-5/.

Get ready for a Picnic, this is our social and member appreciation event for the year! Feel free to bring family, but be sure to reach out with the number of attendees, so we can provide food for everyone. There will of course be food, music, games and fun! Event is held rain or shine, we have a covered shelter house reserved for the event. Agenda --- Moderators Kimberly Deal - Columbus Atlassian User Group Leader Kevin Stanley - Columbus Atlassian User Group Leader Greg Sprowls - Columbus Atlassian Community Leader Hosted By Kimberly Deal, Atlassian User Group Leader Kevin Stanley, Chief Everything Greg Sprowls, Agility Lead --- Global Partner Atlassian (http://atlassian.com) Millions of users globally rely on Atlassian products every day for improving software development, project management, collaboration, and code quality. For over a decade, Atlassian customers have come together to network, share ideas, solve problems, and find new ways to use Atlassian products. Today, more than 15,000 people take part in Atlassian community events in more than 30 countries. --- Complete your event RSVP here: https://ace.atlassian.com/events/details/atlassian-columbus-presents-annual-columbus-ace-summer-picnic/.

We are bringing Microsoft Build sessions to Columbus Ohio! The Central Ohio Azure Meetup and Central Ohio .NET Developer's Group (CONDG) are coming together to bring some of the labs and breakouts from Microsoft Build to your backyard. In this free, 1 day event, you are going to Build stuff with us! And yes, there will be free food. Please RSVP via [Microsoft Build //localhost:columbus | Microsoft Reactor](https://developer.microsoft.com/en-us/reactor/events/27247/).

**Important time note:** Please plan on arriving between 5:30 and 6:00 as the elevators lock after 6 and you'll need to message us and we'll need to come get you. The building address is 4450 Bridge Park The entrance is 6620 Mooney St, Suite 400 You will need to scan your ID at the door to get a visitor badge. **Abstract** *Customize the IDE: Building Extensions for Visual Studio Code* Visual Studio Code is one of the most widely used development environments today, and much of its flexibility comes from its extension ecosystem. Extensions allow developers to customize the editor with new features, integrations, and workflow improvements tailored to their needs. In this session, we’ll cover what extensions are and the different types available, including full extensions written in TypeScript or JavaScript, along with lighter-weight extensions such as color themes, language packs, language support, code snippets, and keymaps. We’ll also look at practical reasons a developer might create an extension, from automating repetitive tasks to adding custom tooling. The session includes a hands-on walkthrough of creating a new extension, testing it locally, and understanding the basic project structure. We’ll close with a brief overview of how extensions are packaged and published to the Visual Studio Marketplace and other distribution options. **YouTube Link** TBD

**Presenter:** Matthew Hess, Microsoft MVP **Time:** Pizza at 6:00, Presentation Starts at 6:30pm Eastern **Location:** Theoris, 9000 Keystone Crossing, Either Downstairs or in Suite 230 if main meeting room isn't available, Indianapolis In 2019 (C# 8.0) Microsoft introduced a feature that has generated a lot of confusion, debate and outright dissent. I'm talking about Nullable Reference Types. In this presentation, I we dig into this feature, explore why it exists, what problem it tries to solve, how it works, and how people have critiqued it, so that you as a programmer can decide if and how you want to use it. Looking forward to seeing you there!

Columbus Code & Coffee is an inclusive, informal co-working session. People of all skill levels attend, and we love it that way. Many people (optionally) bring projects to work on, and many other people (optionally) socialize the entire time. It's entirely up to you! **What to Expect at the Intro Circle** \~\~\~\~\~\~\~\~\~\~\~\~\~ Near the beginning of the event (1:30 pm), we do a standup: * Organizer announcements, updates, and logistics Round 1 - (7 secs max): * Your name * What you're working on * What you can help others with Round 2: * Community events you wanna plug. If none, that's cool too. Round 3: * Job opportunities you're hiring for OR announce that you are looking for one. If none, that's cool. After the introduction circle, everything is self-organized! Feel free to work alone, pair up, attend one of our workshops/presentations, or mingle!

We are going to build together with all the CLIs! E will be doing it at Columbus Code and Coffee Agenda --- Hosted By James Power, Organizer Pete Gordon, Organizer Just a Software Guy in the age of the Internet. Complete your event RSVP here: https://gdg.community.dev/events/details/google-gdg-columbus-presents-ai-improv-lets-build-a-game-together-with-claude-code-codex-and-gemini-and-be-the-judge/.