Kyrylo Karaulnyi’s Post

🟢 The "Hard Truth" About React Native Performance Most React Native performance issues are self-inflicted. It’s rarely the framework's fault. It’s usually how we’re using it. If your app feels sluggish, it’s likely not a limitation of the bridge or the architecture—it’s a result of these three common pitfalls: 1. The "Re-render" Loop We often forget that every state update triggers a render. If you aren't using React.memo, useMemo, or useCallback strategically, you’re forcing the engine to do 10x the work it needs to. 2. Bloated State Management Storing every minor UI toggle in a global store (like Redux or Zustand) is overkill. Global updates for local problems lead to massive, unnecessary component tree re-evaluations. Keep state as close to the component as possible. 3. The "Library for Everything" Trap Need a simple checkbox? Install a library. Need a basic animation? Install a library. Every dependency adds weight to the JS bundle and complexity to the shadow tree. High-performance apps are built by mastering the primitives, not by stacking npm packages. LEARNING OF THE POST: 🔴 Efficiency > Quantity: Optimization starts by reducing what React has to track, not adding more tools. 🔴 Keep it Local: Global state is for global data; component state is for component logic. 🔴 Own your code: Dependencies should be a last resort, not a first step. ""The Senior Mindset: Stop looking for a "magic fix" in the next React Native version. Start profiling your own code. Performance isn't a feature you add at the end; it’s a discipline you maintain during development."" What’s the most common "self-inflicted" performance bottleneck you’ve seen lately? 👇 #ReactNative #MobileDevelopment #SoftwareEngineering #Coding #Performance #Javascript

Most React developers write code that works. Few write code that *lasts*. After building 50+ React projects, here are the patterns that separate good developers from great ones: **1. Stop overusing useEffect** Most side effects don't belong there. If you're syncing state with props using useEffect, you're creating bugs before they happen. Derive state directly instead. **2. Colocate your state** State that only one component uses should live in that component — not in a global store. Lifting state too high is one of the biggest performance killers I see in codebases. **3. Memoize intentionally, not defensively** Wrapping everything in useMemo and useCallback isn't optimization — it's noise. Profile first. Optimize what actually hurts. **4. Build for readability, not cleverness** Your future self (and your team) will thank you. A component that's easy to understand is easier to maintain, debug, and scale. **5. Treat your custom hooks like APIs** Clear inputs, predictable outputs, single responsibility. If your hook is doing three things, it should probably be three hooks. React isn't hard. Writing *maintainable* React is where most developers plateau. The developers companies want to hire aren't just shipping features — they're building foundations other people can confidently build on top of. Which of these do you struggle with the most? Drop it in the comments — let's talk through it. #ReactJS #FrontendDevelopment #WebDevelopment #JavaScript #SoftwareEngineering

I just published a new article on my blog: “What Is NestJS and Why So Many Backend Developers Use It in 2026” NestJS is one of those frameworks that keeps coming up when people talk about building clean and scalable backend applications with Node.js and TypeScript — and for good reason. In this post, I share my thoughts on: what NestJS actually is why it has become so popular what makes it useful when backend projects start growing in complexity This is also the beginning of a NestJS series I’m working on, where I’ll explore the framework progressively, from beginner concepts to more advanced backend architecture topics. Excited to keep building and writing more around backend engineering, system design, and practical development patterns. #NestJS #NodeJS #TypeScript #Backend #SoftwareDeveloper #TechWriting #Engineering #FullStackDeveloper

❌ 5 Mistakes Every React Native Beginner Makes. 1️⃣ Deep nesting of components Too many <View> → inside <View> → inside <View> makes layout slow. 2️⃣ Using too many re-renders (missing memoization) Missing React.memo, useCallback, useMemo = wasted renders. 3️⃣ Overusing setState Store only essential state. Derive the rest. 4️⃣ Heavy work on JS thread Large loops, JSON parsing, timers → freeze UI. Move heavy tasks to native or use libraries like react-native-reanimated, react-native-mmkv, or Background tasks. 5️⃣ Not using FlatList properly Missing keyExtractor, getItemLayout, or using inline functions hurts scroll performance. Use FlatList’s optimization props + memoize item components. Avoid these → your apps will instantly feel faster. React Native isn’t tough… Bad patterns make it tough. #ReactNativeTips #Performance #LearningJourney #JavaScript| #ReactNative #RN

Why NestJS is a Game-Changer for Backend Development In today’s fast-growing web development world, building scalable and maintainable backend systems is more important than ever. This is where NestJS comes into play. As a developer, I’ve been exploring modern backend technologies, and NestJS truly stands out as a powerful framework built on top of Node.js. What is NestJS? NestJS is a progressive Node.js framework used for building efficient, scalable, and enterprise-grade server-side applications. It uses TypeScript by default, which helps developers write cleaner and more maintainable code. Why Developers Love NestJS ✅ Modular ArchitectureNestJS follows a clean and organized structure using modules, controllers, and services — making large applications easy to manage. ✅ Built with TypeScriptStrong typing helps catch errors early and improves code quality. ✅ Inspired by AngularIf you have experience with Angular, NestJS will feel very familiar due to its dependency injection and architecture. ✅ Powerful EcosystemSupports tools like: Express.js Fastify Microservices WebSockets GraphQL APIs ⚙️ Real-World Use Cases NestJS is widely used for: REST APIs Real-time chat applications Enterprise backend systems Microservices architecture My Learning Experience While working on full-stack projects, I realized that choosing the right backend framework is crucial. NestJS not only improves code structure but also makes scaling applications much easier. If you're coming from MERN stack, learning NestJS can take your backend skills to the next level. Are you using NestJS in your projects? Let’s connect and share experiences! #NestJS #NodeJS #BackendDevelopment #FullStackDeveloper #WebDevelopment #JavaScript #TypeScript #SoftwareEngineerir

🚀 Express.js vs NestJS — Which one should you choose? If you're a Node.js developer, you've probably worked with or heard about both Express.js and NestJS. Let’s break it down 👇 ⚡ Express.js Minimal & unopinionated framework Full control over project structure Huge ecosystem & middleware support Best for: small apps, quick APIs, beginners 👉 Pros ✔ Lightweight ✔ Easy to start ✔ Flexible 👉 Cons ❌ No built-in architecture ❌ Hard to scale for large projects 🧱 NestJS Built with TypeScript & modern architecture Inspired by Angular (modular structure) Comes with built-in features (DI, Pipes, Guards, etc.) Best for: large-scale & enterprise apps 👉 Pros ✔ Clean architecture ✔ Scalable & maintainable ✔ Built-in best practices 👉 Cons ❌ Learning curve ❌ Slightly heavy for small apps ⚔️ Final Verdict 🔹 Use Express.js → if you want speed & simplicity 🔹 Use NestJS → if you want structure & scalability 💡 Pro Tip: Many companies start with Express and later migrate to NestJS as the project grows. 👉 Which one do you prefer? Comment below 👇 #NodeJS #ExpressJS #NestJS #BackendDevelopment #WebDevelopment #JavaScript #TypeScript #DevOps

During my experience in backend development, I noticed a clear difference between using Node.js directly and using NestJS as a framework built on top of it. 🔹 Node.js Node.js is a powerful and flexible runtime. However, in large-scale projects, it can become somewhat “chaotic” if strict standards and architectural guidelines are not enforced by the development team. The absence of a well-defined structure may lead to: • Inconsistent coding styles. • Difficulty in maintenance and scalability. • Increased complexity as the project grows. 🔹 NestJS On the other hand, NestJS provides a well-structured architecture inspired by concepts such as Dependency Injection and Modular Design, which helps in: • Organizing code in a clear and scalable manner. • Improving maintainability and testability. • Standardizing development practices across teams. • Accelerating the development of large-scale applications. 💡 Conclusion While Node.js remains an excellent choice for small or highly flexible projects, NestJS is often the better option for medium to large-scale applications that require a robust, maintainable, and scalable architecture. #NodeJS #NestJS #BackendDevelopment #SoftwareArchitecture #WebDevelopment #JavaScript #TypeScript

🚀 Why I’m Moving from NestJS to tRPC (for Full-Stack TypeScript Apps) I’ve built a lot of projects with NestJS—and honestly, it’s powerful, structured, and production-ready. But recently, I started asking myself: 👉 Do I really need all this abstraction for every project? So I tried tRPC… and it changed my workflow. Here’s a quick comparison 👇 🔴 NestJS (Typical Flow) @Post('create-user') createUser(@Body() dto: CreateUserDto) { return this.userService.create(dto); } You’ll still need: DTOs Validation pipes Separate frontend types API contract syncing 🟢 tRPC export const appRouter = router({ createUser: publicProcedure .input(userSchema) .mutation(({ input }) => createUser(input)), }); And just like that: Your types flow from backend → frontend automatically No duplicated interfaces No guessing API responses 💡 What made me consider the shift: End-to-end type safety (this one is huge) Less boilerplate Faster development for full-stack apps Feels more “connected” than traditional API layers ⚖️ But let’s be real: NestJS still shines for: 👉 Large-scale apps with complex architecture 👉 Microservices 👉 Public APIs tRPC shines for: 👉 Full-stack TypeScript apps (React, Next.js, etc.) 👉 Internal tools, dashboards, MVPs For me, it’s not about “NestJS is bad” — far from it. It’s about choosing the right tool for the job. Right now, tRPC feels like the better fit for speed + developer experience ⚡ Curious—if you’re using NestJS today, would you consider trying tRPC? #TypeScript #NestJS #tRPC #WebDevelopment #FullStack #SoftwareEngineering

Lately I’ve been integrating Claude Design into my development workflow, and it’s honestly been a game changer. Working on a full-stack project with TypeScript, NestJS, React, PostgreSQL, and Prisma can get complex pretty fast—especially when trying to keep everything clean, scalable, and consistent across the stack. What I’ve found really powerful about Claude Design is how it helps bridge the gap between idea and implementation. Some highlights from my experience so far: It accelerates UI/UX thinking by turning rough concepts into structured, usable designs. It pairs incredibly well with Claude Code, making it easier to move from design to actual implementation without losing context. It helps maintain consistency across components, which is huge when working with React at scale. It reduces the mental overhead of switching between design and development tools. What I appreciate most is how it complements the development process instead of interrupting it. It feels less like “another tool” and more like an extension of how I think through problems—especially when structuring features across a NestJS backend and a React frontend. Still exploring its full potential, but so far it’s been a solid boost in both productivity and clarity. Curious if others are already using Claude Design + Claude Code in their workflow—what’s been your experience? #AI #Claude #ClaudeAI #ClaudeDesign #ClaudeCode #SoftwareDevelopment #WebDevelopment #FullStack #TypeScript #NestJS #ReactJS #PostgreSQL #Prisma #DevTools #Productivity #UXDesign #UIDesign #TechInnovation

🚀 Mastering React Fundamentals: Components, JSX, Props vs State & More If you're learning React or preparing for frontend interviews, these core concepts are your foundation  1. Components React apps are built using reusable building blocks called components. Think of them as small, independent pieces of UI that make your code clean and scalable. 2. JSX (JavaScript XML) JSX allows you to write HTML-like syntax inside JavaScript. It makes UI development more intuitive and readable. Example: const element = Hello, World!; 3. Props vs State     Props (Read-Only) Passed from parent → child Used to make components reusable     State (Mutable) Managed inside the component Used for dynamic data (like form inputs, counters, etc.) Simple rule: Props = external data State = internal data 4. Functional vs Class Components     Functional Components (Modern React) Simpler & cleaner Use Hooks (useState, useEffect) Preferred in today's development     Class Components (Legacy) More complex (uses this keyword) Lifecycle methods (componentDidMount, etc.) Mostly used in older codebases 📌 One-line takeaway: Functional components + Hooks have replaced class components in modern React. 🔥 Why this matters? Mastering these basics helps you: ✔ Crack frontend interviews ✔ Build scalable React apps ✔ Write cleaner, maintainable code 💬 What concept did you struggle with the most while learning React? #React #FrontendDevelopment #JavaScript #WebDevelopment #ReactJS #Coding #100DaysOfCode #SoftwareEngineering