Let's be honest—traditional A/B testing is broken. If you've ever implemented client-side testing, you know the drill. Your users load the page, wait for JavaScript to execute, and then—flicker—the content changes. It's jarring. It hurts your Core Web Vitals. And worst of all, your experiments might be measuring user frustration instead of genuine engagement. But what if you could run A/B tests with zero flicker? What if you could modify your HTML before it even reaches the browser? That's exactly what Cloudflare Workers make possible . The Server-Side Advantage A/B testing at the edge means making decisions about which variant a user sees before any HTML is sent to their browser . Instead of: Load the page Execute JavaScript Flicker Apply the variant Track the result You get: Decision made at the edge Correct HTML streamed immediately Zero flicker Better performance Companies like Ninetailed are already using Cloudflare Workers to achieve 2-3x cost savings compared to traditional serverless platforms, all while delivering personalized experiences with minimal latency . How It Actually Works The concept is surprisingly elegant. Your Cloudflare Worker intercepts incoming requests, checks for a cookie to maintain user consistency, and routes users to the appropriate variant . Here's a simplified version that's production-ready: javascript const NAME = "myExampleWorkersABTest"; export default { async fetch(req) { const url = new URL(req.url); // Determine which group this user is in const cookie = req.headers.get("cookie"); if (cookie && cookie.includes(`${NAME}=control`)) { url.pathname = "/control" + url.pathname; } else if (cookie && cookie.includes(`${NAME}=test`)) { url.pathname = "/test" + url.pathname; } else { // New user—randomly assign them (50/50 split) const group = Math.random() < 0.5 ? "test" : "control"; url.pathname = `/${group}` + url.pathname; // Fetch and modify the response to set a cookie let res = await fetch(url); res = new Response(res.body, res

Recentemente percebi uma coisa meio curiosa: eu simplesmente tinha um problema ao consumir o conteúdo do 4noobs do jeito que ele é organizado hoje. Não porque a organização seja ruim — muito pelo contrário. Acho que a comunidade fez um trabalho incrível organizando o projeto. O ponto é que eu percebi que meu jeito de estudar é diferente: tenho muito mais facilidade quando consigo seguir listas, trilhas ou um caminho de aprendizado mais visual. Foi aí que pensei: "Se esse problema existe para mim, talvez exista para mais alguém. E se, de quebra, eu aproveitar isso para praticar consumo de APIs?" Foi assim que nasceu a Central 4noobs . A proposta era simples: consumir todo o conteúdo disponível no GitHub do 4noobs e apresentá-lo de uma forma que fizesse mais sentido para o meu jeito de estudar, organizando os materiais em listas e trilhas de aprendizado. A ideia nunca foi substituir a organização do projeto original, mas oferecer uma forma diferente de navegar pelo mesmo conteúdo. Essa era a ideia inicial... mas, como acontece com praticamente todo projeto pessoal, ela foi crescendo conforme o desenvolvimento avançava. Mas ainda é uma alternativa . Tenham em mente isso. :) O que aprendi durante o projeto O projeto foi desenvolvido utilizando Next.js , TypeScript , Drizzle ORM e Supabase como banco de dados (e hoje já não tenho tanta certeza se essa foi a escolha mais inteligente 😅). O maior aprendizado foi entender melhor como funciona o consumo de APIs. Antes eu entendia o conceito na teoria (com o próprio 4noobs , inclusive), mas foi durante o desenvolvimento da Central que realmente comecei a compreender como tudo se conecta. Depois desse projeto, passei a enxergar melhor como uma API é estruturada e, principalmente, como consumir seus dados sem simplesmente despejar tudo na tela. Outra parte interessante foi aprender a tratar os dados recebidos. Uma coisa é receber uma resposta gigantesca da API. Outra completamente diferente é filtrar apenas as informações que re

This is Lowpass by Janko Roettgers, a newsletter on the ever-evolving intersection of tech and entertainment, syndicated just for The Verge subscribers once a week. "AI is the new frontier for us," says Marc DeBevoise, who took over as the new CEO of OverDrive last week. OverDrive is best known for the ebook lending app […]

All the Apple products avoiding the price hike (for now)

You have seen this loop before. An agent starts a “simple” task, say scrape listings, refactor a repo, research a market, or whatever. It fails, it retries, it re-reads context, it apologizes and tries all over again. Twenty minutes in and the dashboard shows six figures of tokens and zero useful outputs or deliverables. The model did not misbehave on purpose. The orchestrator never had a hard budget gate with an ROI in mind. Skillware v0.4.0 ships a new skill for exactly that gap: monitoring/token_limiter . It lets you monitor and limit any agent’s token budget in real time — Gemini, Claude, OpenAI, DeepSeek, Ollama, custom Python loops, you name it. Same skill, same JSON, any runtime. What Skillware is in a nutshell Skillware is an open registry of installable agent capabilities . Each skill is a bundle: skill.py — deterministic Python ( execute() returns JSON) instructions.md — when the model should call the tool manifest.yaml — schema, constitution, issuer Tests and docs — shipped in the wheel You load by ID, adapt for your provider, call execute() on tool use. The model decides when , the skill decides how , predictably, every time. That split matters for budget control. You do not want the LLM guessing whether it is “allowed” to spend more tokens. You want a small, auditable function that answers: continue, warn, or stop. Meet the Token Limiter This skill is a budget gate , not a kill switch wired into OpenAI or Anthropic. After each model turn, your host loop passes cumulative usage. The skill returns one of three actions: Action Meaning CONTINUE Under the soft threshold — keep going WARN Approaching the limit (default 80%) — tighten scope FORCE_TERMINATE Hard ceiling hit — stop the loop Important nuance: the skill does not cancel API sessions or kill processes. It returns a structured decision. Your orchestrator must act on it. That is by design — Skillware skills stay portable and provider-neutral. No skill-specific API keys. No network calls. Pure Python m

My dashboard had a useMemo doing arithmetic it had no business doing. It was a Pokémon TCG Pocket collection tracker, but that part doesn't matter. What matters is that the home page needed to show three things: overall completion, completion per set, and which set you were closest to finishing. The way I'd built it, the browser was fetching every card and every owned record, then grinding through the math on each render to figure all of that out. It worked. It also got slower and harder to read every time the data grew or I added a metric. So I moved the aggregation out of React and into Postgres, and the surprising result was that my frontend got boring . Fewer hooks, less state, almost nothing left to break. That's the whole argument of this post: aggregation belongs in the database, and when you put it there, the React code that's left over is the kind of boring you actually want in the layer your users touch. What "fetching everything into React" actually looks like Here's the shape of the original dashboard. Load all the cards, load the user's owned rows, then derive everything on the client. const [ cards , setCards ] = useState < Card [] > ([]); const [ owned , setOwned ] = useState < OwnedCard [] > ([]); useEffect (() => { ( async () => { const { data : allCards } = await supabase . from ( " cards " ). select ( " * " ); const { data : ownedRows } = await supabase . from ( " user_cards " ) . select ( " card_id " ); setCards ( allCards ?? []); setOwned ( ownedRows ?? []); })(); }, []); const ownedIds = useMemo (() => new Set ( owned . map (( o ) => o . card_id )), [ owned ]); const perSet = useMemo (() => { const groups : Record < string , { total : number ; have : number } > = {}; for ( const card of cards ) { const g = ( groups [ card . set_id ] ??= { total : 0 , have : 0 }); g . total += 1 ; if ( ownedIds . has ( card . id )) g . have += 1 ; } return groups ; }, [ cards , ownedIds ]); const overall = useMemo (() => { const total = cards . length ; const ha

When most people hear Bitcoin , the conversation usually starts with price. But for developers, Bitcoin is much more than a chart. Bitcoin is a distributed system operating without a central authority. It combines networking, cryptography, game theory, economics, and software engineering into a protocol that has remained operational for years while processing value globally. As a software developer, what fascinates me most is not speculation it’s the architecture. Some concepts every developer can appreciate: ⚡ Distributed Consensus Thousands of nodes independently verify the same rules without trusting each other. 🔐 Cryptography in Practice Digital signatures make ownership verifiable without revealing private keys. ⛏️ Proof of Work A mechanism that converts computation into security and coordination. 🌍 Open Source at Global Scale Anyone can inspect the code, run a node, contribute, or build on top of the ecosystem. 📦 Immutability Through Design Data integrity is achieved through incentives, validation rules, and chained blocks. Studying Bitcoin changes how you think about: System reliability Security models Network design Incentive structures Building software that survives failure Whether you plan to build in blockchain or not, Bitcoin is worth studying because it teaches principles that extend far beyond finance. Curious to hear from other developers: What concept in Bitcoin architecture changed the way you think about software systems?

If you've ever wondered how to visualize, teach, or explore keyboards without owning physical hardware, a keyboard simulator is the answer. In this in-depth guide, we explore what keyboard simulators are, how they work, and why they are changing the way people learn to type. Defining a Keyboard Simulator A keyboard simulator is a software application that digitally recreates the visual, functional, and interactive behavior of a physical keyboard. Unlike a simple on-screen keyboard that merely serves as a typing aid, a true keyboard simulator renders the keyboard in detail — often in three dimensions — and responds to keystrokes in real time, creating an immersive and educational experience. The best keyboard simulators go far beyond static images. They animate individual key presses, replicate the visual design of specific keyboard models, support multiple layouts (QWERTY, Dvorak, AZERTY), and even show animated hands performing the typing — making them extraordinarily useful for remote teaching, accessibility testing, content creation, and learning to type. 💡 Did you know? The Keyboard Simulator by Roboticela is one of the most advanced free and open-source keyboard simulators available today, featuring 3D interactive rendering powered by React Three Fiber, five authentic laptop keyboard models, and eight beautiful visual themes. The Core Components of a Keyboard Simulator A fully-featured keyboard simulator typically includes several key components that work together to create a complete experience: 🎮 3D Rendering Engine: Displays the keyboard model from any angle with smooth rotations and zoom capabilities. ⌨️ Real-Time Key Feedback: Every keystroke on your physical keyboard mirrors instantly on the 3D model. 🖐️ Hand Animation: Animated hands show proper finger placement and movement as you type. 📝 Document Editor: A built-in text editor captures your input and links it to the keyboard visualization. 🎨 Theme System: Multiple visual themes make the experience beau

Extreme heat coupled with humidity will make it feel like 109 degrees Fahrenheit as the holiday weekend approaches.

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X has launched a hosted MCP server, making it easier for developers to connect AI applications with the company’s API.

Stealthy startup Arcturus uses lasers to infuse carbon nanomaterials into copper, dramatically improving its ability to conduct electricity.

Users will be able use AI to create newsletters based on their recordings.

Engineers on the new team will embed within companies to deploy purpose-built agents, focusing on fast deployments and customer self-sufficiency.

Hi everyone, french web dev here, About 10 years ago I did a little party game in the browser inspired by Achtung die Kurve genre, it reached HN ( https://news.ycombinator.com/item?id=9494619 ) and everything went crazy, it's still largely played in open-spaces all over the world today. This past year, I've been working on a sequel: https://curvytron2.com is live. Same goal as the first one: challenge myself, perfect my skills, have fun and give back to the internet community the best way I know