📅 Tuesday, December 9, 2025, WarsawJS Meetup #133 [Best for JavaScript Developers, Frontend Engineers & AI-Curious Makers] [FREE]

The final WarsawJS meetup of 2025 arrives with a particularly strong lineup, featuring deep technical insights, live demos, and hands-on lessons shaped by real-world engineering challenges. Hosted at DataArt Warsaw inside the WeWork Mennica Legacy Tower, this edition brings together JavaScript practitioners, AI builders, mobile developers, and tooling experts for an evening dedicated to practical knowledge and community exchange. As one of Warsaw’s most established tech meetups, WarsawJS continues its tradition of elevating the ecosystem with talks that blend theory, engineering craft, and open discussion.

This session focuses on four high-impact themes currently defining the JavaScript and broader software landscape: the rise of AI app builders, the evolution of cross-platform testing, the shifting dynamics among modern package managers, and the personal reflections of developers who teach and mentor others. Whether you’re exploring the limits of React Native’s testing frameworks, rethinking your dependency tooling, or curious about how AI architectures behave under production constraints, the meetup offers a dense program designed to deliver both practical takeaways and community inspiration.

🔍 What to Expect

In this three-hour onsite meetup, participants will gain exposure to the architecture and challenges behind rapid AI-powered product creation, explore next-generation testing approaches for React Native, and compare modern package management strategies in depth. The evening concludes with a reflective talk on how teaching others reshapes an engineer’s own growth—an increasingly relevant topic as senior developers take on mentorship roles in scaling teams.

Networking opportunities, sponsor showcases, and informal QA time with speakers are integrated throughout the program.

Session Breakdown

1. AI App Builder — Deep Dive by Daniil Volosyuk

Daniil explores Monday Vibe, an AI app builder, demonstrating how the product creates value for users and what architectural principles power it under the hood. The session covers pipeline design, model orchestration, prompt engineering strategies, and the engineering challenges that emerged during development. Participants will gain visibility into how real AI products behave at scale and what pitfalls teams commonly encounter when building generative systems.

2. Write Once, Test Everywhere: Cross-Platform Testing for React Native, by Szymon Chmal

Testing React Native traditionally forces teams into uneasy trade-offs: Jest provides speed, but runs outside native environments; end-to-end tools provide realism, but introduce heavy operational overhead. Szymon presents React Native Harness, a new framework enabling Jest-style tests to run on actual devices and simulators—with access to native modules and without mocks by default. Attendees will learn how this shifts the testing landscape and what it means for developer experience, release confidence, and CI strategies.

3. State of Package Managers, by Anton Morozov

Anton leads a deep technical comparison between npm, pnpm, and bun, analyzing their performance characteristics, dependency management structures, migration paths, and use-case trade-offs. Through code exploration and live metrics, participants will walk away with a clear sense of when each tool shines and how to plan transitions for production environments. This session is ideal for teams preparing to modernize their tooling stack or address performance and reliability issues within existing workflows.

4. “What Teaching Others Taught Me, by Michał Mickiewicz

Michał delivers a reflective talk on how teaching programming reshaped his perspective on learning, problem-solving, and long-term professional growth. He discusses how explaining concepts to beginners sharpens one’s own technical intuition and how mentorship cycles strengthen engineering culture inside teams. The talk resonates especially with senior engineers, educators, and developers transitioning into leadership roles.

Speaker Profiles

Daniil Volosyuk — AI engineer and product builder specializing in generative applications, system design for AI-enhanced platforms, and fast-iteration prototyping.

Szymon Chmal — React Native specialist focused on testing frameworks and cross-platform developer tooling. Known for impactful contributions to mobile development workflows.

Anton Morozov — JavaScript tooling expert with deep knowledge of package managers, build pipelines, and performance-optimized development environments.

Michał Mickiewicz — Developer and educator whose work bridges engineering practice and the craft of teaching.

Additional Notes

• Event is held onsite at DataArt Warsaw, WeWork Mennica Legacy Tower (Room 01C), Prosta 20, 00-850 Warszawa.

• Language: English

• Registration: Free

• Sponsors: Xfaang, DataArt

• Partners: JetBrains, Webellian

• Media partner: K MAG

📍 Logistics

City: Warsaw

Start time: 18:30

Event type: Meetup

Topic: JavaScript

Main link: https://www.meetup.com/Microsoft-Azure-Users-Group-Poland/events/312249648/

[JavaScript, software engineering]