Understanding JWT Authentication in Web Apps

How do you migrate a frontend on a healthcare platform that can't go down? You don't rewrite everything at once. You run both frontends in parallel and switch pages one by one. We've been running AngularJS and Next.js side by side in production — same backend, same authentication, same users. A single JSON config file controls which pages open in the old UI and which in the new. No downtime, no big-bang risk. The key decisions that made this work: * nginx routing layer that proxies to two different frontends based on the config * HTTP-only cookies on a shared domain for seamless authentication across both * A per-user "Turn on new UI" toggle so anyone can switch back instantly * Graceful degradation — fallback to old UI without config We call it "the switch". Inspired by how PrivatBank migrated their web UI in the 2010s, designed by me, implemented by Michael Balakhon — he turned the concept into a working production system. Part 2 of my migration series. Full technical details, nginx configs, and the cookie domain trap that caught us in production. Link to the full article in the first comment 👇 #nextjs #angularjs #nginx #migration #webdevelopment #healthcareit #legacy

🚀 Built a Smart Auth System (Frontend Only) Just wrapped up a project where I implemented a complete authentication system using React + Vite + TailwindCSS. 🔐 Key Highlights: • User Registration & Login Flow • Real-time Form Validation • Strong Password Rules (uppercase, lowercase, number, special character) • Password Strength Indicator (Weak → Strong) • Clean & Responsive UI 💡 Focus was on writing clean validation logic and improving user experience with instant feedback. This project helped me understand how real-world auth systems work on the frontend before integrating backend APIs. Next Step → Connecting it with backend & JWT 🔥 Github Repo: https://lnkd.in/gZXz8K3e #ReactJS #FrontendDevelopment #WebDevelopment #JavaScript #CodingJourney

What if your frontend became lighter and your backend more secure — without adding complexity? That shift is already happening in the JavaScript ecosystem. 🔵 React Server Components are approaching a stable release. By rendering on the server, they reduce the amount of JavaScript sent to the browser and minimize hydration overhead. The result? Faster, more scalable applications with improved performance out of the box. 🟢 Node.js is introducing a Permission Model with fine-grained runtime flags like --allow-fs-read and --allow-net. This brings a true least-privilege approach to backend security — without requiring heavy configuration or additional tooling. Together, these advancements are shaping a future where performance and security are built-in defaults, not afterthoughts. This is a quiet but significant evolution — a “silent upgrade” that could define the next generation of web applications. Are you already experimenting with React Server Components or Node.js permission flags? I’d love to hear your experience 👇 #ReactJS #NodeJS #WebPerformance #AppSecurity #JavaScript #WebDevelopment #SoftwareEngineering

🚀 Just published a new article on Medium! If you're working with React and APIs, you've probably heard of Axios, but do you really know why it's so widely used? In this article, I break down: ✅ How Axios simplifies API requests ✅ Built-in error handling (and why it matters) ✅ Why it’s often preferred over fetch Whether you're a beginner or sharpening your frontend skills, this will give you a clearer understanding of making efficient API calls in React. #React #JavaScript #WebDevelopment #Frontend #Axios #SoftwareEngineering

REST APIs — Explained for Frontend Developers When building web applications, the frontend does not directly communicate with the database. It communicates with a backend server through APIs. This post covers the basics of REST APIs: • What an API is • What REST means • HTTP methods (GET, POST, PUT, DELETE) • Request and Response • Status codes • JSON data format • How frontend, backend, and database connect Understanding APIs is essential for building real-world applications, because this is how the frontend and backend communicate. 📌 Save this for revision. #WebDevelopment #FrontendDeveloper #BackendDevelopment #JavaScript #React #NodeJS #RESTAPI #LearningInPublic #Consistency

Most state management problems are self-created. Not technical limitations. Here’s the clarity that changed how I build React apps 👇 There are only 2 types of state: Server State → Comes from APIs → Needs caching, syncing, refetching Client State → UI-specific → Local interactions Where things go wrong: ✖ Server state pushed into global stores ✖ UI state unnecessarily shared ✖ Everything treated as “global” What I do instead: ✔ Use React Query for server state ✔ Keep UI state local by default ✔ Promote to global only when necessary Result: → Less complexity → Better performance → Easier debugging Senior engineering is not about managing more state. It’s about managing less of it. #ReactJS #StateManagement #FrontendArchitecture #JavaScript #SoftwareEngineering #CleanCode

A common mistake I see in many React projects: Developers often fetch data inside multiple components, which leads to: • repeated API calls • inconsistent data • poor performance A better approach is using centralized data fetching with tools like TanStack Query. It helps with: ✔ caching ✔ background updates ✔ cleaner code Small improvements like this can make a big difference in real-world applications. If anyone needs help with React frontend development, feel free to message me. #reactjs #frontenddeveloper #webdevelopment

💡 Understanding Node.js + Express.js Architecture (Simplest Way) If you're getting started with backend development, one of the most important things to understand is how request flow works in a Node.js application using Express.js. Here’s a simple breakdown: 🔹 A client (browser or mobile app) sends an HTTP request 🔹 The Express server receives the request 🔹 Middleware processes it (authentication, logging, validation) 🔹 Routes direct the request to the correct controller 🔹 Controllers handle the logic and interact with business logic 🔹 Business logic communicates with the database 🔹 Finally, a response is sent back to the client 👉 In short: Client → Server → Middleware → Route → Controller → Database → Response This architecture is lightweight, scalable, and widely used in modern web applications. 📌 Pro Tip: Keep your code modular by separating routes, controllers, and services for better maintainability. #NodeJS #ExpressJS #BackendDevelopment #WebDevelopment #SoftwareArchitecture #JavaScript #APIDesign #Coding

💡 What actually happens when you click a button on a website? Many people use web applications every day, but few think about what happens behind the scenes after a single click. Here is a simple breakdown of a typical React + Node.js request flow: User Click   ↓ React (Frontend)   ↓ fetch("/api/...")   ↓ Express Server (Node.js)   ↓ Server Logic / Database   ↓ JSON Response   ↓ React Updates UI   ↓ User Sees Updated Page Explanation 1️⃣ User clicks something in the React interface   2️⃣ React sends a request using fetch("/api/...")   3️⃣ Express receives the request on Node.js   4️⃣ The server processes the request and returns JSON   5️⃣ React updates the UI without refreshing the page  ⚡ This seamless communication between frontend and backend powers modern web applications. #WebDevelopment #ReactJS #NodeJS #ExpressJS #FullStackDevelopment #JavaScript

TanStack Start is, I think, the best framework utilising React. Everything is type-safe by default, even the 'to' prop that you pass to the 'Link' component provided by the framework which is equivalent to the 'href' attribute or prop you may have used in the past. Moreover, the seamless integration with the other libraries by TanStack makes the framework more attractive. Honestly, you feel it as you build things. The amount of over-head you have to deal with when trying to integrate, for example, TanStack Query with Next.js just makes you throw it away and start-over from scratch using TanStack Start. I am desperately waiting for it to be stable and use it on production websites. Furthermore, I do think TanStack Start has the potential to give a head-to-head challenge to Next.js or even replace it when it comes to data-intensive websites where you are constantly interacting with APIs 'cause you simply cannot build such websites with the data fetching abilities that you get with Next.js at the moment. I hope there is good competition in the future, and things do not get shoved down frontend developers' throats like server components or server functions for example. Let me know in the comments what you think of all of this.