CEO @margelo_com – core contributor @reactnative – angel investor - wannabe racing driver - I built VisionCamera, Nitro Modules and react-native-mmkv
Vienna, Austria
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- Followers 20,761
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gear shifter, because it's easier to find than to aim for a 4cm wide area on a fully flat surface.
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After 4 months of hard work, we just finally launched react-native-filament!!!!!!!!!!!! 🥳🚀
Check out margelo/react-native-filament, and build amazing 3D react-native apps today! 🚀
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React Performance Tip #12: Since modern CPUs are square, format your code to exact squares to make sure it fits on the CPU as efficiently as possible.
This ensures that the CPU can directly execute the optimized format and will execute code much faster! 🤯
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Built with VisionCamera. All the drawing and blurring is happening with JavaScript code, and it runs in realtime. No post-processing. This is going to change the entire mobile camera game. Get ready.
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We'll launch react-native-filament this week - a blazingly fast physically based 3D rendering engine built with C++ for React Native! 🚀
As a teaser, here's a 47 line component to load a 3D model from the web, render it and rotate, pan and zoom into it using gesture handler! 🤯
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React Native made my dreams come true - I bought my dream car!
I want to thank everyone who put their trust in me and my skills. ❤️
See y'all on the race track!
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This is a React Native app running on my Mac, which uses my iPhone as a remote Camera over the air. 🤯
All made possible by react-native-vision-camera!
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.@lauridskern and I rebuilt Doodle Jump in React Native — the main game loop runs in a Reanimated useFrameCallback(), and everything renders using Skia. Runs pretty smooth! 🤩
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Just created a PR that makes every react native app start much faster on Android! (400ms in our case) 🤯🚀
github.com/facebook/react-na…
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Finally got something to show - we're working on a new 3D library for React Native! 👀🧊
👉 Powered by native Graphics APIs (Metal/Vulkan)
👉 Full control over rendering in JS
👉 120 FPS rendering on a Worklet Thread (no lags!)
👉 Supports hotswapping .glb/.gltf models
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This is an object detector model running in React Native VisionCamera.
I am looping through all the output data and drawing red boxes using simple JavaScript - even the model can be hotswapped!
All of this while still running at more than 60 FPS 🤯 - no more native code!!
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Working on an all new way to write native code for React Native.
"Nitro Modules" will provide first-class Swift support, insanely fast C++ bindings, object-oriented/instance-based approach, and much more coming soon! stay tuned 👀🤫
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🧵 #ReactNative Performance Pro Tip 🔥💡: If you are building a #ReactNative app that works with Crypto, Big Numbers or Buffers make sure you are using the right libraries - otherwise your app will be slow asf! 😷 (a thread) (1/5)
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(1/5) I'm super excited to announce 𝗿𝗲𝗮𝗰𝘁-𝗻𝗮𝘁𝗶𝘃𝗲-𝗻𝗶𝘁𝗿𝗼-𝗶𝗺𝗮𝗴𝗲 - an all new Image component for React Native, built entirely with Nitro Views! 🖼️🥳🚀
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After months of hacking, I am finally releasing Nitro Modules to the public... 👀
Fasten your seatbelt and get ready for Nitro!!! 🚀🥳
github.com/mrousavy/nitro
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My PR is now shipped in React Native 0.79 - Android apps now start ~12% faster! 🔥
React Native 0.79 is now available!
This release includes several performance improvements. Metro is now >3x faster to cold start! Android apps will also be faster thanks to changes to JS bundle compression.
reactnative.dev/blog/2025/04…
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VisionCamera V3 is up to 𝟳𝘅 faster than V2 because of performance improvements like:
- New CameraDevice selection API (no await) 🚀
- Rewritten native codebase (cleaner & faster) 🧹
- Single-hardware-locking for configuration batches (instant updates) 🔒
- ..and more!
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The power of VisionCamera's write-back Frame Processors: I detect all faces in a Frame, then immediately censor them out using a simple frame.drawRect(..) call - all in JavaScript! 🤯
This is running in real-time, and with a faster model (like BlazeFace) it can run at 200+ FPS 🔥
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I just released VisionCamera V4!!!!!! 🥳🚀💪🤯🔥👏
This one's a big release. With V4 you can draw directly onto a Camera Frame using Skia!!!
..and also, I fixed pretty much all Android issues from V3. 😉
github.com/mrousavy/react-na…
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Is React Native easy?
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react-native-graph v1 is out! Tons of performance improvements and rewritten drawing logic to make it more flexible 🔥
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still can't believe how smooth VisionCamera + Skia is - this face blur Skia filter runs in a JS Frame Processor at 120 FPS!
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VisionCamera V3 is out 😍🥳🥹🎉 github.com/mrousavy/react-na…
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ah yes, a youtube link.
let me just open the in app browser, then safari, then youtube to watch it
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I just built an app to detect humans and draw them as stick figures using VisionCamera V3 + TFLite + Skia! 🕺
Check out the blog post here: mrousavy.com/blog/VisionCame…
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In 2021 I built react-native-mmkv
In 2022 I built VisionCamera V3
In 2023 I built VisionCamera V4
In 2024 I built Nitro Modules
What's next for 2025?
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I just released react-native-fast-tflite!!! 🥳
🔥 Powered by JSI/C++
💨 Zero-copy ArrayBuffers
🔧 Uses the low-level C/C++ TFLite core API
🔄 Supports fast-refresh for swapping out .tflite models at runtime
🖥️ Supports GPU-acceleration
github.com/mrousavy/react-na…
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Many React Native devs don't know how to get relevant log or crash information for creating issues in open source libs, so here's some tips for y'all! 💡
First; There's multiple types of crashes.
1. In JS there's mostly just Errors which have a message and a stacktrace. Those are easy and can be thrown and caught. The stacktrace shows you where the error originated from (function names file names and even line numbers!)
2. On Android, you'll get Java Exceptions, which are pretty similar to JS-errors, they also have stacktraces (often looks like com.mrousavy..camera.CameraView)
3. On iOS, you'll get NSExceptions (often looks like *** NSInvalidArgumentException: something) which have a code, domain and optionally a user info, but no stacktrace.
4. On both iOS and Android you might also get C segfaults (eg "SIGABRT") which are coming from a LLVM-based language like C or C++. They are not handle-able and crash the app because the code tried to do something which is not possible (eg tried accessing memory which already has been deleted).
👉 For JS and Java errors, always post the stacktrace.
👉 For NSExceptions, always post the exception name (NSInvalidArgumentException), code (helps googling), and domain/message.
👉 For segfaults (eg SIGABRT), run the app in Xcode/Android Studio with a debugger attached (Xcode; just run, Android Studio; press the 🐞 icon), and when the app goes into a segfault you can see a stack trace on the left side of the screen. You can even interactively step through this to see where it is coming from, often you just need to step a few methods back to find the caller.
Also, native logs are needed for more info.
They are not in Flipper or React Dev Tools, they are inside Xcode (bottom logs tab) or Android Studio (logcat window).
Paste them along with your crash info to give more information.
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imo this is why this approach is wrong and makes it insanely difficult to find something in a project. same for 'index.js'.
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I just released react-native-mmkv 3.0.0 stable - mmkv is now the first pure C++/CxxTurboModule! 🥳github.com/mrousavy/react-na…
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WWDC 2024 demonstrated once again why native frameworks like React Native are just better than custom frameworks like Flutter.
Features like the text summary will be baked into UITextView, and a React Native app will support it from day 1.
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Use react-native-mmkv, it is the fastest key/value storage solution for React Native! 🔥
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I just wrote a blog post on how to build an app that detects objects at 60 FPS purely with React Native / JavaScript! 🚀
mrousavy.com/blog/Reinventin…
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I finally released Nitro Views!!!! 🥳🚀 github.com/mrousavy/nitro/re…
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React Native + native-vision-camera is pretty much as fast as a fully native Camera app.
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• TurboModules, Fabric and faster bundlers coming soon
• Camera Frame Processing, 2D Skia Graphics drawing and 60 FPS Animations straight from JS
• Easy Swift/Kotlin Native Modules abstraction coming soon (@expo)
#ReactNative is about to become a whole lot more interesting
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don't wanna build up too much hype but I'll post a video soon that'll make every single one of you go: 😳😍😲 #ReactNative
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Good news! My PR to react-native core for smooth, interactive keyboard dismissal in ScrollViews now landed on master again! 🎉🎉
Can't wait to see my change in the next #ReactNative release 🤩
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You're probably having a lot of unnecessary re-renders in your #ReactNative app 🥶🥶🥶
There's a simple flip you can switch to greatly improve the overall performance and responsiveness of your app and here's how you can switch it on. 🚀💨 (1/4)
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JSI is amazing - I'm passing the whole audio sample buffer to JavaScript and then run an algorithm that determines the average "loudness" of the audio in realtime (in JS!) 🤩 can anyone guess what song this is? #ReactNative #javascript @expo
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Just released VisionCamera 3.0.0-rc.4! 🎉
- Full rewrite of the C++ codebases 😅
- New hook: useSkiaFrameProcessor 🔗
- Frame Processor Plugins are now object-oriented 💪
- Android now works! 🤖
- Frame Processors are now fully optional! ⛓️
github.com/mrousavy/react-na…
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My `automaticallyAdjustKeyboardInsets` PR has landed in React Native core!!
github.com/facebook/react-na…
Y'all excited to finally have smooth interactive keyboard swipe-down in #ReactNative lists?
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Shopify, a billion dollar company bets on React Native - and you should too.
It’s been a while since we’ve done an update on @shopifyeng + mobile + @reactnative, so let’s do it.
shopify.engineering/react-na…
A thread 🧵
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I'm excited to announce that we just published react-native-quick-crypto - a new library for #ReactNative that implements NodeJS' crypto library in native C++/JSI! 🥳🎉🚀
We measured up to 58x speedups in certain cryptography functions, check it out: github.com/margelo/react-nat…
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Benchmark time - ObjC TurboModule vs Swift Nitro Module... 😳🥵
- TurboModules: 220ms
- Nitro: 29ms 🔥
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These Reanimated gestures are just so damn smooth 😍 @swmansion
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React Native Pro Tip: you can use Terminal escape codes to print to 𝚌𝚘𝚗𝚜𝚘𝚕𝚎.𝚕𝚘𝚐 with color, background, or even as bold text! 🔥
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Just published clean-rn which will clean all React Native (native Android + native iOS) caches in your project!
github.com/mrousavy/clean-rn
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JSI allows JavaScript to directly call native C++ code.
#ReactNative's new UI Manager "Fabric" uses JSI to render views even faster - it's powered by the native C++ Layout Engine "Yoga".
Yoga layouts views ~7 times faster than AutoLayout, the layout engine for native iOS apps.
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Part of being an app developer is running to your local tech shop just to find a phone that can reproduce a rare crash by running a custom .apk on each one of them 😅📱
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Swift is coming to Android!!! 😳🥳
Announcing the Swift on Android Working Group, with the goal of establishing and maintaining Android as an officially supported platform for Swift. More here: forums.swift.org/t/announcin… #Android
ALT An illustrative screenshot of Swift on Android.
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just did a talk at React Native Berlin about VisionCamera + Skia - thanks for having me @hubraum! 💪🇩🇪
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ExpoModules vs TurboModules vs NitroModules 🔥
In the 𝚊𝚍𝚍𝙽𝚞𝚖𝚋𝚎𝚛𝚜(...) benchmark, NitroModules is 𝟱𝟵𝘅 𝗮𝘀 𝗳𝗮𝘀𝘁 as ExpoModules and 𝟭𝟱𝘅 𝗮𝘀 𝗳𝗮𝘀𝘁 as TurboModules! 🤯
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VisionCamera now has an @expo config-plugin to easily enable the fully native QR/Barcode scanner! 🔍
Simply set 𝚎𝚗𝚊𝚋𝚕𝚎𝙲𝚘𝚍𝚎𝚂𝚌𝚊𝚗𝚗𝚎𝚛 to 𝚝𝚛𝚞𝚎, and you're all set! ✅
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spent the past few weeks being hyper-focused on learning SwiftUI
- Code w/ SwiftUI 10h a day
- Watch 3+ WWDC videos a day
- Read all Apple docs
- Browse apple developer forums
- Build all things from scratch
- Don't rely on AI
Can recommend.
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I just released ShadowLens to the AppStore!!! 🥳🥳
Download now: apps.apple.com/at/app/shadow…
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this is an absolute game changer for the entire JavaScript industry. get ready
We wanted to show the performance and the insane power of the Static Hermes native FFI. But we don't yet support the all language features needed to compile React Native (soon though!), so we improvised.
We imported the bindings for DearImGui (a popular C++ imperative game UI library that renders meshes), and Sokol (an amazing lightweight 3D backend in C) and wrote a small demo.
"Imperative UI" means that the entire UI and the state of the screen is recreated on every frame, which suits our purposes to demonstrate SH very well.
The demo runs 100% compiled native code. JavaScript runs in every frame and recreates the entire state of the screen. It is portable to all platforms, though the screen layout is not optimized for phone.
We wrote the demo in C++ and in JS, to compare, and they both ran with the same performance.
In the attached videos you can see the demo running at the stable screen refresh rate - 120Hz on my Mac, 60Hz on a old Moto G5 phone.
It includes some widgets, an n-body simulation of planets, a playable game demo, etc.
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gm, here's a smooth rounded graph with 200 data points running at 60 FPS with React Native Skia 👏 (built for @PinkPandaDefi at @margelo_io) @ShopifyEng
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A pro tip: Read "Effective Modern C++".
Even if you're not a C++ developer, this book will help you understand how memory management works and believe it or not this affects how you think about React (Native).
In fact that's the only programming book I ever read
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VisionCamera 3.0.0-rc.3 is out! 🥳🎉
It contains the TensorFlow Lite JS Plugin for everyone to try now! 📸
Also some stability improvements and Skia is now on latest version with the new Ganesh rendering pipeline 😎
github.com/mrousavy/react-na…
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As a React Native developer you at least need to understand how to read Logcat/Xcode logs. Nothing ever crashes silently.
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VisionCamera now has an integrated, blazingly fast QR-code/Barcode scanner! 🤯 github.com/mrousavy/react-na…
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