Callstack presents
REACT UNIVERSE CONF
September 2-4 / 2025
Wrocław, Poland
BRINGING WORLDS TOGETHER
We bring developers and tech leaders come together to explore the latest trends, exchange insights, and push the boundaries of what's possible with React and React Native.
Experience in-depth discussions on full-stack development with React and get practical insights on cross-platform app development with React Native. Explore the tools, techniques, and best practices not to be heard elsewhere.

















RUC 2025 SPEAKERS

Dr Kubilay Ahmet Küçük


Kræn Hansen


Khalef Hosany


Vladimir Morozov



Violina Popova


Xuan Huang


Neil Dhar


Fernando Rojo


D. Richard Hipp


Fernando Rojo
Head of Mobile at Vercel. Previously co-founder of BeatGig, a marketplace for booking live music. Prior to BeatGig, Fernando's startup was part of Y Combinator's W19 batch. While in college at UPenn, he founded PATOS Shoes – a sneaker brand that sold in over 15 countries, and was featured in J. Crew, Forbes, Buzzfeed, NBC, and more. Rojo is the maintainer of many open source React libraries, including Solito, Moti, Dripsy, Zeego, and Burnt.

Xuan Huang
Xuan is a software architect on the Lynx family of technologies, where he can dream of making interfaces better for more users, more developers, and more machines. Before joining ByteDance, he worked on React Core ("React Forget"), React Native, Hermes and Reason during his time at Meta.

Violina Popova
With a passion for creating seamless cross-platform experiences, my journey in tech started not with programming, but as a consultant in the tech industry. The desire to build and innovate led to a shift in focus towards software development, particularly mobile app development, where the thrill of solving complex problems and crafting user-friendly applications became a calling. Co-founding Frontend Queens was a natural extension of this journey, inspired by a commitment to inclusivity in tech. This community was born from the belief that everyone, especially women, should have the opportunity to thrive in technology. By fostering a supportive environment, we aim to empower women to break barriers and pursue fulfilling careers in this ever-evolving field.
Is your app built on guesswork, or do you have data to back up your decisions? In this talk, we'll dive into A/B testing in React Native and how we at ClipMyHorse.TV use experimentation to optimise our app. Learn how to design and implement meaningful tests, analyse results, and shift from intuition-based development to data-driven decision-making.

Vladimir Morozov
The Node API is an API for building native add ons for Node.JS. It is JS Engine agnostic, and ABI stable, which makes it very versatile and what allows alternative runtimes like Deno and Bun to target Node compatibility. In React Native Windows, we have maintained a fork of Hermes that reimplements JSI on top of the Node API. We have been working with the community to bring this integration to the rest of React Native. Come learn more about what this unlocks, and how much farther you can take your app with the full power of both Hermes and Node-API together!

Khalef Hosany
II am an engineering manager at Microsoft and my team works on React Native for desktop and the integration of React Native into Microsoft Office. We also contribute to upstream React Native, help drive open-source releases and participate in several React Native related working groups. am an engineering manager at Microsoft and my team works on React Native for desktop and the integration of React Native into Microsoft Office. We also contribute to upstream React Native, help drive open-source releases and participate in several React Native related working groups.
The Node API is an API for building native add ons for Node.JS. It is JS Engine agnostic, and ABI stable, which makes it very versatile and what allows alternative runtimes like Deno and Bun to target Node compatibility. In React Native Windows, we have maintained a fork of Hermes that reimplements JSI on top of the Node API. We have been working with the community to bring this integration to the rest of React Native. Come learn more about what this unlocks, and how much farther you can take your app with the full power of both Hermes and Node-API together!

Kræn Hansen
Kræn is a senior software engineer at MongoDB contributing primarily to Realm JS and its related packages and holds a M.Sc.Eng. from the Technical University of Denmark. He's main contributions has been to the Realm JS SDK, Realm Studio (data browsing Electron / React app) and the React frontend for the (now deprecated) Realm Cloud.Kræn lives 30 minutes west of Copenhagen, with his wife and their two 4 year old twin girls. They recently added yet another newborn girl to their pack.

Dr Kubilay Ahmet Küçük
Dr. Küçük is a computer scientist who spent 10 years at Oxford University in various research positions focusing on systems security. He is the author of the “Confidential Remote Computing” paradigm and previously received grants from Intel Corporation for his TEE-related work. Previously, he was a research engineer at ETH Zürich, delivering C++-based industrial software products in the areas of Industry 4.0, simulation, and digital twin technologies. Alongside his teaching activities at Oxford, he is currently exploring independent opportunities.
Although C++ offers a wide range of computational libraries with various capabilities and enables high-performance computing, there are long-standing challenges in integrating them into a React Native project. To address these challenges, we developed a practical set of tools and a sustainable methodology for automating an all-in-one solution for using C++ libraries in cross-platform JavaScript applications.
Manually compiling, porting, and bridging a library is not only difficult but also unscalable in enterprise settings. For large corporations and commercial products, using C++ in React Native should not introduce additional complexity or make projects fragile. Instead, the React Native community needs a stable, permanent, long-term solution that works in a scalable manner while offering reliability.
With cpp.js, developers can include many pre-ported C++ libraries into React Native or WebAssembly projects by simply including the relevant header files. While the Codegen project already supports C++ bridging in React Native, it is limited to function calls and primitive types. In contrast, we offer Object-Oriented Programming (OOP) support and modern C++ features (C++11 & C++14), enabling integration with a broad range of widely-used C++ libraries. For example, we have successfully integrated GIS libraries such as GDAL into React Native, demonstrating cpp.js’s practical effectiveness. With little to no effort, cpp.js can support the long-term maintenance of various C++ libraries, thanks to our automation processes. This minimises the traditionally difficult engineering work of cross-compiling, porting, and bridging libraries to JSI.
Following the introduction to our toolset, architectural decisions and development journey, we will show;
(1) how to quickly write and execute native C++ code within a JavaScript environment,
(2) utilising and importing ready-to-use native C++ libraries from our cpp.js repository. Further, for developers in more sophisticated cases,
(3) we will show how to port a C++ library you need using our toolset, even if the C++ library has external dependencies. This showcases modularity, independence in maintenance, the scalability characteristics of our project, further giving developers more control.
We warmly welcome collaboration and feedback from the React Native community. Although this talk focuses on React Native, cpp.js is a cross-platform solution that also supports WebAssembly (web, Node.js, Cloudflare Workers, etc.), alongside mobile platforms. We will cover these broader aspects in our upcoming talks.
CONFERENCE
TIMELINE
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Feel the vibe


EPIC AFTER PARTY
The React Universe Conf wraps up with an unforgettable Afterparty! Enjoy a sizzling BBQ, an open bar, great music, and, of course, the legendary dev karaoke.



NETWORKING
Our venue is designed to help you connect, collaborate, and get to know one another. Need a break from all the buzz? Unwind in a chill zone where you can relax and recharge.







BLAST FROM THE PAST
- 2024
- 2023
- 2022
- 2021
- 2020
- 2019
- 2018
- 2017
React Universe Conf is brought to you by Callstac, a software consultancy that helps companies ship faster and scale smarter with React and React Native.
Founded just months after React Native went open source, Callstack has been part of this ecosystem since the beginning and has been shaping it ever since. Over 200 engineers work with enterprises and small businesses alike to build high-performing apps for every platform - iOS, Android, tvOS, visionOS, web, and beyond. We build in the React Universe: one full-stack, cross-platform codebase that runs everywhere - hence the name of this conference.
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