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PWA with React + Leaflet: lessons from a 31-city map app

Notes from shipping a real-world PWA in Korea:Vite SSG is worth it. SPAs lose Korean SEO because Naver's crawler doesn't fully render JS.Leaflet > Mapbox for cost-sensitive projects. Free OSM tiles + zero cost.Firebase Hosting rewrites let you have deep URLs (/city/suwon) without a backend.KakaoTalk share is non-negotiable in Korea — 70%+ of social traffic.PWA install banner: don't auto-prompt, let the user discover.Project: https://gyeonggi-currency-map.web.app?ref=devto&utm_source=devto

What is the cost of making a mobile app?

The cost of making a mobile app depends on your goals, features, and the platforms you choose. A simple app with basic functions like login, user profiles, and notifications usually costs less than an app with advanced features such as AI, live chat, payment systems, or real-time tracking. This is why many businesses work with experienced mobile app development services to plan the right features before development starts.A basic app may cost between $10,000 and $30,000, while a medium-sized app

This Week In React #292 : Octane, TanStack, StableRef, Next.js | Workers, SafeAreaView, backgroundImage, WebGPU | TC39, Web Vitals

Hi everyone, Seb and Jan here 👋!This week we have an interesting React challenger, keeping its mental model but compiled ahead of time. Also various major announcements from the TanStack side.On the mobile side, we have interesting RN 0.87 PRs to look at, discussions around workers / worklets, a WebGPU/Skia integration, and React Navigation 8 / Screens 5 progress.Last week, many proposals progressed during a TC39 meeting. npm is going to scan for malware at publish time. Core Web Vitals will now

TypeScript `readonly` Arrays and Tuples: When Immutability Saves You and When It Fights You

TypeScript readonly Arrays and Tuples: When Immutability Saves You and When It Fights YouThis article was written with the assistance of AI, under human supervision and review.Most readonly bugs stem from misunderstanding what the type actually prevents. Developers mark an array readonly, ship it to production, and discover that nested objects still mutate freely—or that function parameters reject their readonly values entirely. The failure mode here is subtle but expensive: you get type s

Building RhythmKey: Creating a Modern Typing Experience with React, Tailwind, and Real-Time Analytics

IntroductionTyping tests are everywhere, but many focus only on one thing:"How fast can you type?"I wanted to build something different.Something that feels like a real typing environment - fast, customizable, and enjoyable.That's how RhythmKey was created.RhythmKey is an open-source typing application built with React, Tailwind CSS, and Vite that combines:Real-time typing analyticsMultiple test modesCustom themesMechanical keyboard soundsSmooth animationsDetailed performance trackingThe g

How I Built a Serverless, In-Browser Image Converter Using the Canvas API

Working with images online often means dealing with a mess of formats. WebP is great for performance, PNG is necessary for transparency, and JPG remains the standard for compatibility. But converting them usually involves uploading sensitive images to a third-party server.I wanted to build a solution that solves this issue directly in the browser. That's why I created PhotoConvert, a client-side tool to convert images between formats instantly without any server uploads. Who Benefits Most?T

I Built the Same i18n App Twice: Here is What Broke the First Time

Why Localization Matters to Me as a Football Fan and DeveloperEvery four years, the FIFA World Cup brings the entire planet together. Billions of fans tune in from almost every country on earth. Like many of you, I am a huge football fan. I also happen to read and speak several languages, and one thing I have noticed over the years is how much more personal and exciting following the tournament feels when you can read match stats, live commentaries, and news in your own mother tongue.But w

Custom element FOUC: the rule that hid nothing

I shipped a CSS rule that could not possibly do its job, looked at the page, saw the flash still happening, and spent longer than I want to admit tuning the wrong thing.The product is Tearline, a small zero-dependency web component I'm building under Kynth. You wrap any HTML in one tag and it renders as a thermal receipt you can export as a PNG:<tear-line barcode="047320260726"> <h1>MERIDIAN</h1> <p>Coffee & Provisions</p></tear-line>Custom elements

From Prompt to Play Store: Rapid Prototyping and Scaling Mobile Apps with WaveMaker AI

In today’s hyper-competitive digital landscape, the speed at which a product team moves from an initial concept to a fully deployed mobile application often determines its market success. However, mobile development remains notorious for its slow velocity—burdened by platform-specific edge cases, complex state management, and repetitive backend wiring.WaveMaker’s AI Agentic App Generator fundamentally alters this dynamic. By combining autonomous generative agents with a low-code visual environme

What’s !important #16: sibling-index() Animations, Use Cases for the infinity Keyword, Container Stuck Queries, and More

In What’s !important #16, see how the soon-Baseline sibling-index() function can be used for animations, revisit the 2026 FIFA World Cup with CSS, explore the use cases for the infinity keyword, learn about container ‘stuck’ queries, and much more.What’s !important #16: sibling-index() Animations, Use Cases for the infinity Keyword, Container Stuck Queries, and More originally handwritten and published with love on CSS-Tricks. You should really get the newsletter as well.

Smart Bitcoin Loan Strategies 2026: Create More Financial Flexibility

Selling your Bitcoin to cover an expense feels like a betrayal of your future self. When you sell 1 BTC today at $70,000, you aren't just making a transaction. You are trading away the potential for that asset to be worth $100,000, $150,000, or more down the line. This is the opportunity cost that keeps long-term holders up at night. Smart Bitcoin loan strategies offer a way out of this dilemma. Instead of selling, you can borrow against your Bitcoin, unlocking the liquidity you need today while

Add website screenshots to your app with a single GET request

You need a thumbnail of a user-submitted URL. Maybe it's a link preview in a dashboard, a visual record attached to a saved bookmark, or a proof-of-state image in an audit log. The usual answer is to install Playwright, ship Chromium into your container, and then own a headless browser in production forever.SiteIntel does that part for you. One GET, PNG bytes back. The request/v1/screenshot takes a full https:// URL (not a bare domain) and responds with image/png:curl -s -X GET \ 'https://

Why your browser game loads to a black screen

Here is a failure that almost nobody catches before shipping, because it does not look like a failure from the inside. Your game works perfectly on your machine. Every file returns 200. There is not a single error in the console. And a player who opens the link sits in front of a black rectangle for the better part of a minute, decides the site is broken, and closes the tab.The short version. A blank canvas with no errors is almost never a crash. It is a game that is still loading, in a framewor

A dependency-free build.js: assembling a static site from JSON data

IntroI run several small information sites that get new data appended every day. I started with a static site generator, but as the number of sites grew, I spent more and more time on things unrelated to the content: framework version bumps, plugin incompatibilities, slow builds. So I switched everything to a dependency-free build.js (Node standard library only) that assembles public/ HTML from data/*.json.What I learned is that static site generation splits cleanly into three layers — dat

Nine Red Tests and No Way to Tell Which Ones Matter

Every SDET I know has a private ritual for the morning after a red nightly, and every one of them is embarrassed by it.Mine went like this. Open the report. Count the failures. Scan the test names. Then, without opening a single stack trace, decide which ones were "probably real" based on nothing more defensible than a feeling about which parts of the app had been touched that week.I called it triage. It was pattern matching on vibes, and I did it every working day for years. The morning th

I built 79 browser tools that never upload your data — here's why client-side matters

Every developer has hit this: you need to resize an image, decode a JWT, or format a messy JSON blob. So you search "online [thing]", land on some tool, and… it wants to upload your file to a server first.For a random stock photo, fine. For a customer CSV, a production JWT, or a screenshot of an internal dashboard? You just handed a stranger's server your data.I got tired of that, so I built SmartTools — 79 small, single-purpose tools that do all the work in your browser. Nothing is uploaded. Ev

Why Cloudflare Acquired Astro And What It Tells You About Where the Web Is Going

Cloudflare is a network infrastructure company. They run DNS, DDoS protection, and CDN services for millions of websites. They are not, historically, a JavaScript framework company.In January 2026, they bought one.Not just any framework, the fastest-growing one in the content-driven web space. And the whole Astro team came with it.This wasn't a charity acquisition. Cloudflare paid to solve a specific problem. Understanding what that problem is tells you more about the future of web development t

Deep Dive: Understanding React's usePrevious Hook…

Originally published at norvik.tech IntroductionExplore the technical details of React's usePrevious hook, its applications, and how it transforms state management in web development. What is the usePrevious Hook?The usePrevious hook in React is a custom hook that allows developers to track the previous value of a state or prop. This can be particularly useful when comparing current and previous values to manage component behavior effectively. It essentially provides a way to access th

Tasklet (YC P26) Is Hiring a Customer Success Engineer

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The End of an Era

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