André Simões

André Simões

@andrejnsimoes.com

Staff Engineer | JNation Organizer https://teklinks.andrejnsimoes.com/

58 followers 283 following180 posts

André Simões reposted

JNation 🇵🇹 May 25 & 26 - 2027

@jnationconf.bsky.social

🚨 CFP closes Jan. 10 — submit NOW! Got a great talk, deep dive, or workshop about Java, JavaScript, AI, Cloud/ops and Security? Want to speak at JNation 2026 in sunny 🌞 Coimbra, Portugal? 👉 Submit your proposal by next Saturday: sessionize.com/jnation-2026

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teklinks.andrejnsimoes.comAgentic Engineering in ActionIn this session, Mitchell Hashimoto walks Richard Feldman through his approach to using AI when building Ghostty. Specifically they went through this recent commit in detail. You can watch their chat on YouTube or read below for some selected quotes.

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teklinks.andrejnsimoes.comProof of Human. Creating the invisible Turing Test for the InternetProof of Human. Creating the invisible Turing Test for the Internet AI systems have detectable behavioral signatures that can be used to improve bot detection. Roundtable's Proof-of-Human API verifies proof-of-human invisibly, continuously, and instantaneously.

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teklinks.andrejnsimoes.comReact Still Feels Insane And No One Is Talking About ItRecently, I did a side project that I wrote about in the other post. As part of it, I had what was supposed to be just a few paragraphs on how React sucks - but I just couldn't stop writing about it.

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teklinks.andrejnsimoes.comProgressive JSONDo you know about Progressive JPEGs? Here’s a nice explanation of what a Progressive JPEG is. The idea is that instead of loading the image top to bottom, the image instead is fuzzy at first and then progressively becomes more crisp. What if we apply the same idea to transferring JSON?

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teklinks.andrejnsimoes.comThe State of React and the Community in 2025Detailed thoughts on how React has been developed over time, and explanations for common community confusion and concerns Introduction 🔗︎ Today, the state of React and its ecosystem is complicated and fractured, with a mixture of successes, skepticism, and contention.

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teklinks.andrejnsimoes.com`document.currentScript` is more useful than I thought.Every so often, I stumble across a well-established JavaScript API in the browser that I probably should've known about years ago. Examples include the window.screen property and the CSS.supports() method. To my relief, I've realized I'm not always alone in my ignorance.

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teklinks.andrejnsimoes.comHow does Kafka know what was the last message it processed? Deep dive into Offset TrackingLet’s say it’s Friday. Not party Friday, but Black Friday. You’re working on a busy e-commerce system that handles thousands of orders per minute. Suddenly, the service responsible for billing processing crashes. Until it recovers, new orders are piling up.

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teklinks.andrejnsimoes.comConnect any React application to an MCP server in three lines of codeYou can deploy a remote Model Context Protocol (MCP) server on Cloudflare in just one-click. Don’t believe us? Click the button below.

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teklinks.andrejnsimoes.comHow we built our multi-agent research systemClaude now has Research capabilities that allow it to search across the web, Google Workspace, and any integrations to accomplish complex tasks.

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teklinks.andrejnsimoes.comOn How Long it Takes to Know if a Job is Right for You or NotA few eagle-eyed readers have noticed that it’s been 4 weeks since my last entry in what I have been thinking of as my “niblet series” — one small piece per week, 1000 words or less, for the next three months. This is true.

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teklinks.andrejnsimoes.comA short history of web bots and bot detection techniquesDid you know your favorite website can detect when you’re browsing it in public transport and when you scroll it laying in your bed? Today we’ll learn how they can do it and how this info is used to fight bots.

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teklinks.andrejnsimoes.comWant to Be a Better Frontend Engineer? Try a Week On-CallYou’re going to hate me for saying this, but I actually like being on-call. I know. I know. But hear me out. Obviously not the part where PagerDuty yanks you out of a dream with your heart pounding. But on-call taught me more about frontend quality than any bug tracker ever did.

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teklinks.andrejnsimoes.comJest 30: Faster, Leaner, BetterToday we are happy to announce the release of Jest 30. This release features a substantial number of changes, fixes, and improvements. While it is one of the largest major releases of Jest ever, we admit that three years for a major release is too long.

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teklinks.andrejnsimoes.comai agentsI'm using agents to write a lot of code now. Just 6 months ago it didn't really work well, so if you haven't tried in a while, this is your sign. Let me explain practically how I've been using them, where they still kind of suck, and what tools I've had success with.

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teklinks.andrejnsimoes.comMy AI Skeptic Friends Are All NutsTech execs are mandating LLM adoption. That’s bad strategy. But I get where they’re coming from. Some of the smartest people I know share a bone-deep belief that AI is a fad — the next iteration of NFT mania.

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teklinks.andrejnsimoes.comSearch Params Are StateSearch params have been historically treated like second-class state. They're global, serializable, and shareable — but in most apps, they’re still hacked together with string parsing, loose conventions, and brittle utils. This works, but it’s manual and repetitive.

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teklinks.andrejnsimoes.comHow Imports Work in RSCReact Server Components (RSC) is a programming paradigm that lets you express a client/server application as a single program spanning over two environments.

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teklinks.andrejnsimoes.comThe Underestimated Power of Hot Spots and Notes in EventStormingI've been facilitating the EventStorming sessions for years now, and something keeps catching my attention.

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teklinks.andrejnsimoes.comHow we built our AI code review agent for IDEsLearn how we redesigned our pipeline to create an AI code review tool for instant IDE reviews, cutting time-to-first-comment by ~90%.

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teklinks.andrejnsimoes.comAnnouncing Vitest 3.2Vitest 3.2 focuses on improvements to Browser Mode and TypeScript support. This release also includes some new useful methods, config options and deprecates the workspace config in favour of projects. In an effort to simplify the configuration, the team decided to deprecate the separate vitest.

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teklinks.andrejnsimoes.comIs It JavaScript?OH: It’s just JavaScript, right? I know JavaScript. “It’s Just JavaScript!” is probably a phrase you’ve heard before. I’ve used it myself a number of times.

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teklinks.andrejnsimoes.comJavaScript's upcoming Temporal API and what problems it will solveJavaScript will soon have a new feature that many developers are eagerly awaiting. The feature is the Temporal API which will fix many problems and inconveniences of the old Date object.

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teklinks.andrejnsimoes.comThe Ingredients of a Productive MonorepoSo! Suppose you’re an intrepid engineer in a nascent Developer Productivity team. Your engineering organization has decided that it wants to move towards a monorepo.

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teklinks.andrejnsimoes.comNine Emerging Developer Patterns for the AI EraYoko Li

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teklinks.andrejnsimoes.comA Look Into the Secrets of MCP: The New Secret Leak SourceThe Model Context Protocol (MCP) is one of the latest advancements in the field of Agentic AI.

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teklinks.andrejnsimoes.comHuman coders are still better than LLMsThis is a short story of how humans are still so much more capable of LLMs. Note that I'm not anti-AI or alike, you know it if you know me / follow me somewhere.

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teklinks.andrejnsimoes.comAnnouncing Rolldown-ViteTL;DR: Try out the Rolldown-powered Vite today by using the rolldown-vite package instead of the default vite package. It is a drop-in replacement, as Rolldown will become the default bundler for Vite in the future. Switching should reduce your build time, especially for larger projects.

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teklinks.andrejnsimoes.comThe Beauty of TanStack RouterChoosing a Router is probably one of the most important architectural decisions we have to make. The router isn't just another dependency in node_modules - it's what holds your whole application together.

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teklinks.andrejnsimoes.comManual Work is a BugA.B.A: always be automating Thomas A. Limoncelli Let me tell you about two systems administrators I know. Both were overloaded, busy IT engineers. Both had many repetitive tasks to do. Both wanted to automate these tasks.

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teklinks.andrejnsimoes.comGitHub for Beginners: Building a React App with GitHub CopilotWelcome to the next episode in our GitHub for Beginners series, where we’re diving into the world of GitHub Copilot. This is our sixth episode, and we’ve covered quite a lot of ground. You can check out all our previous episodes on our blog or as videos.

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teklinks.andrejnsimoes.comI think the ergonomics of generators is growing on me.I like the "syntactic sugar" JavaScript's seen over the past decade (arrow functions, template literals, destructuring assignment, etc.). I think it's because most of these features solved real pain points for me (some of which I didn't even know I had).

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teklinks.andrejnsimoes.comAnnouncing TypeScript Native PreviewsThis past March we unveiled our efforts to port the TypeScript compiler and toolset to native code. This port has achieved a 10x speed-up on most projects – not just by using a natively-compiled language (Go), but also through using shared memory parallelism and concurrency where we can benefit.

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teklinks.andrejnsimoes.comA Brief History of JavaScriptThis year, JavaScript turns 30. Within three decades, JavaScript went from being a weird little scripting language developed in 10 days to the world's most popular programming language. Here are some key moments in its history to show how JavaScript has evolved and where it is headed.

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teklinks.andrejnsimoes.comThe efficiency trap: Why obsessing over AI productivity will destroy your engineering cultureArtificial intelligence is everywhere in software development. From GitHub Copilot to Claude Code, companies are integrating AI into their engineering workflows at breakneck speed. The promise? Faster code delivery, fewer bottlenecks and higher productivity.

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teklinks.andrejnsimoes.comIceland approved the 4-day workweek in 2019: nearly 6 years later, all the predictions made have come true.In 2019, Iceland made headlines by becoming one of the first countries in the world to adopt the four-day working week, not through a general law, but through agreements allowing workers to negotiate shorter weeks or reduced hours. Five years on, the results are indisputable.

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teklinks.andrejnsimoes.comWorking on Complex SystemsHello! Today, let’s discuss a fascinating topic: complex systems. Throughout my career, I’ve worked in many complicated environments. For instance, I worked on optimizing driver-passenger matching in ride-hailing at a Uber's competitor. This context, like others, was technically challenging.

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teklinks.andrejnsimoes.com#Start using RslibWe provide the scaffold tool create-rslib for quickly creating Rslib projects. This scaffold supports creating Node.js / React library projects and supporting development tools. Additionally, we provide migration documentation to help users migrate from other build tools to Rslib.

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teklinks.andrejnsimoes.comHow Promises Work in JavaScriptPromises in JavaScript may feel like an abstract or magical thing that handles the async work for us. Once you get into them, they're relatively easy to use, but not that easy to understand what's really happening.

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teklinks.andrejnsimoes.comWhy performance optimization is hard workI’m not talking about skill, knowledge, or convincing a world focused on radical acceleration that optimization is necessary. Performance optimization is hard because it’s fundamentally a brute-force task, and there’s nothing you can do about it.

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teklinks.andrejnsimoes.comThe Curse of Knowing How, or; Fixing EverythingIt starts innocently. You rename a batch of files with a ten-line Python script, or you alias a common git command to shave off two keystrokes. Maybe you build a small shell function to format JSON from the clipboard.

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teklinks.andrejnsimoes.comConcurrent Optimistic Updates in React QueryLook, I can instantly append a task to a list when I press Enter on the input field. That's great in theory, but in practice, there's likely more challenges awaiting you. I have already written a bit about this in #12: Mastering Mutation in React Query, but it's an important point to re-iterate on.

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teklinks.andrejnsimoes.comImpossible ComponentsSuppose I want to greet you in my favorite color. This would require combining information from two different computers. Your name would be coming from your computer. The color would be on my computer.

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teklinks.andrejnsimoes.comWhy Do We Have a Cache-Control Request Header?I’ve written and spoken many, many times about the Cache-Control response header and its many directives, but one thing I haven’t covered before—and something I don’t think many developers are even aware of—is the Cache-Control request header.

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teklinks.andrejnsimoes.comRSC for Astro DevelopersOkay, so in Astro you have two things: Astro Components: They have the .astro extension. They execute exclusively on the server or during the build. In other words, their code is never shipped to the client.

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teklinks.andrejnsimoes.comRobust Data Fetching Architecture For Complex React/Next.js AppsMost of us underestimate data fetching complexity until it’s too late. Many projects begin innocently with useEffect() and fetch() sprinkled across components.

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teklinks.andrejnsimoes.comCategorize Your DependenciesWhen building a project, it’s very likely that we will install third-party packages from npm to offload some tasks. On that topic, we know there are two major types of dependencies: dependencies (prod) and devDependencies (dev). In our package.json, it might look something like this:

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teklinks.andrejnsimoes.comHow Node.js Works Behind the ScenesIf you know how JavaScript works behind the scenes in the browser environment (I highly recommend you check this 15-minute read article if you don't know), it's relatively easier to understand unlike Node.js. It doesn't have a bunch of phases or so on. But why does Node.

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teklinks.andrejnsimoes.comThe Hidden Cost of AI Coding“The best moments in our lives are not the passive, receptive, relaxing times… The best moments usually occur if a person’s body or mind is stretched to its limits in a voluntary effort to accomplish something difficult and worthwhile.

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teklinks.andrejnsimoes.comBuilding An Offline-Friendly Image Upload SystemAmejimaobari Ollornwi 9 min read Serverless, JavaScript, User Experience Share on Twitter, LinkedIn Devs love Storyblok - Learn why! How To Measure UX and Design Impact, with Vitaly Friedman Enterprise UX Masterclass, with Marko Dugonjic JavaScript Form Builder — Create JSON-driven forms without