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I compared 1,489 eSIM plans in 199 countries. Price per GB varies 105x

Disclosure: we run Bitcall, which sells travel eSIMs. The prices below come from our own catalogue, so read them as one provider's prices on one date, not a survey of the market.We wanted to answer a simple question: how much does mobile data cost a traveller around the world? We had the data on our own site, so we turned it into a small price index. Here is how it works, with the code and a few things that surprised us. 1. The data was already structuredEvery destination page on our site c

I Built an AI 3D WebGL Portfolio Generator That Gives You Full Source Code Export

Hey everyone! 👋Like many developers, I noticed a frustrating tradeoff when creating a technical portfolio:Option A: Spend 40+ hours coding a custom website from scratch and maintaining it whenever you finish a new project.Option B: Use generic website builders that give you flat 2D templates, charge high monthly fees, and lock your code inside proprietary walled gardens.To solve this, I built MyFolio — an AI-powered 3D spatial portfolio generator that transforms your GitHub repositories and PDF

How Flingkeep turns a pointer gesture into a controlled throw in JavaScript

Flingkeep is our browser castle-defense game built around grabbing and throwing invading stick figures. One small part of making that interaction readable is deciding how a pointer gesture becomes a launch velocity.This walkthrough follows the current JavaScript implementation in our separate browser submission build. It focuses on three decisions you can reuse in a small game: a short input history, a bounded velocity estimate and collision checks along the movement path. Use the end of th

Build an AI Shopping Agent That Knows What a Deal Costs

Originally published at ForgeMesh.An AI shopping agent needs current product data, a way to compare like-for-like offers and an honest account of missing costs. ShopScout supplies search, product lookup, offer comparison and shipping-plan tools through an HTTP API and an MCP wrapper. This guide shows how to connect them to a tool-capable agent without tying the design to one chat model. Build around the tool contract, not one chat brandThe useful boundary is between the model that reasons a

A tiny deep-link trick so my Instagram stories open the exact game (3,000 games, 25 lines of JS)

This is not rocket science, and many of you have probably done it a hundred times. But it solved a real, annoying problem for me in 10 minutes, so I'm sharing it in case it helps someone else. 🙂 The problemI run PlayCombo, a small site with around 3,000 free HTML5 games split into 13 category pages. The games are loaded from a JSON list and rendered with plain JavaScript inside WordPress.Every day I post a story or a short video on Instagram, Facebook and YouTube showing one game. Then I ad

How to create an XML sitemap from a URL list

An XML sitemap is a list of public URLs that you want search engines to discover. It can help with discovery, but it does not guarantee crawling, indexing or rankings. Start with the sitemap your site already hasIf your site uses a CMS, check whether it already generates a sitemap. WordPress, Wix and other platforms can maintain one as pages are added or removed. Use that sitemap rather than creating a second file that will go stale.A manual sitemap makes sense when you have a small site, a

Building a Zero-Lag Swiss Tax & Salary Calculator in Next.js (Why We Kept Everything in Browser Memory)

If you’ve ever looked at how taxes and social contributions work in Switzerland, you know it’s notoriously decentralized. There are 26 cantons, each with its own municipal tax multipliers (Steuerfuss), varying church taxes, multiple withholding tax tariffs (Quellensteuer), and statutory pension rules that change based on your exact age bracket.When building LivingSwiss, an expat analytics and financial tool suite, our initial instinct was to treat this like a standard backend system: send the us

I let Muse ship an app on SnoozeStack. Here's the whole thing.

Why I did thisI created SnoozeStack — a backend platform with a specific bet: most developers don't have one app with a million users, they have ten apps with a hundred users each, and the infrastructure tax per project is what kills the other nine.I wanted to test out Meta's new Muse AI Assistant and thought having it start from zero and setup a working public site on SnoozeStack would be a great test. If the platform is actually agent-friendly, an agent should be able to drive it end to

How to Install Node.js on Windows, Mac and Linux (Complete Guide)

I spent a weekend debugging a "node: command not found" error because I'd skipped a step in the Node.js install. So I wrote down everything I wish I'd known.If you want the version with OS-detection tabs and troubleshooting, here's the full guide:👉 How to Install Node.js on Windows, Mac, and LinuxHere's the short version. Which version should you install?Always install LTS (Long Term Support). It's stable, tested, and supported for years. Skip "Current" unless you need bleeding-edge feature

I built a browser wave-survival FPS with Three.js — no download, just open and play. 8 weapons, 7 enemy types, custom B* pathfinding, endless boss waves. If you enjoy it, a star would really help it get discovered: https://github.com/guangzhoueven/fps

GitHub - guangzhoueven/fps: 一个有趣，好玩的原创FPS游戏。 · GitHub 一个有趣，好玩的原创FPS游戏。. Contribute to guangzhoueven/fps development by creating an account on GitHub. github.com

Eighteen hand-drawn SVG spots that invert on a dark panel without taking a single prop

Nakodo is built as a field guide to YouTube creators, so the interface is meant to look like a naturalist's notebook: a kingfisher called Alcy, tagged specimen entries, plate numbers, hatching instead of grey fills. All of it is drawn in React components rather than exported as assets, and the rule that made the whole set maintainable is that a spot illustration takes no colour props at all.This is the design-engineering half of the product. There is no clever algorithm in here, just a small set

useRef in React

Understanding useRef in ReactuseRef is one of the built-in Hooks in React that allows us to store a value that persists between component renders. The main difference between useRef and useState is that changing a ref value does not cause the component to re-render. Because of this, useRef is useful when we want React to remember a value, but we do not want that value change to update the UI. A ref can also be used to directly access a DOM element, such as an input, button, or div. Ho

useEffect in React

What is useEffect?useEffect is a React Hook that runs code after a component renders.Some common use cases are:Fetching data from an APIUpdating the document titleWorking with localStorageSetting up timersAdding event listenersSyntaximport { useEffect } from "react";useEffect(() => { // Code}, []);The first argument is a function containing the code we want to execute.The second argument is called the dependency array. useEffect with an Empty Dependency Arrayimport { useEffect } f

TypeScript Contracts for Reliable Email Test Fixtures

Email tests usually start as a small helper: create an address, wait for a message, click a link, and move on. A few months later, that helper has become a hidden dependency for signup, password reset, billing, and notification tests. The failures are then hard to read because the test does not know whether the problem was the UI, the mail provider, or cleanup.The fix is to treat an email fixture as a product-like resource with a clear contract. In a TypeScript and React codebase, the type shoul

I Built AgentVerse: An Agentic Analytics Platform Using AI Agents and MCP

What if you could ask your analytics dashboard a simple question:"Why did sales decrease last month?"Instead of manually filtering charts, exploring datasets, and writing database queries, imagine a system that could understand your question, generate a query, validate it, analyze the results, and present the findings with a visualization.That idea inspired me to build AgentVerse, an agentic analytics platform that combines AI agents, MongoDB, and the Model Context Protocol (MCP).I built this pr

I built a 100% client-side JSON to CSV converter because I didn't trust web converters with sensitive API logs

Hey everyone,As a developer, I frequently need to flatten nested JSON exports and API responses into CSV format for analysis. Almost every free online tool I found uploads raw JSON data to backend servers for processing.If you are handling customer data, API keys, or internal logs, that's a security risk.I built DataFlex Studio (https://dataflexstudio.vercel.app) using Next.js and Web Workers.How it works:• Runs 100% inside your browser using background threads.• Handles recursive unwrapping of

How I Built 50 Web Interactions Without Turning My React App Into a Performance Nightmare

How I Built 50 Web Interactions Without Turning My React App Into a Performance NightmareI kept rebuilding the same small interaction ideas for different projects.A magnetic button.An image that reacts to the cursor.A menu transition.A scroll-controlled composition.A little physics experiment for typography.The individual effects were fun. The problem was that each project ended up with its own component, its own assumptions, and its own implementation details.Eventually I realized I wasn'

How We Built PORCELE: A Modern Next.js E-Commerce Platform for Smart Bathroom Technology

How We Built PORCELE: A Modern Next.js E-Commerce Platform for Smart Bathroom TechnologyHow We Built PORCELE: A Modern Next.js E-Commerce Platform for Smart Bathroom TechnologyBuilding an e-commerce website for a physical product is very different from building a typical marketing website.For PORCELE, the goal was to create a premium digital experience for smart toilets while also building the technical foundation required for dynamic products, shopping carts, checkout, payments, responsive inte

Frontend machine coding rounds: the 5 patterns I would practice first (with code)

Machine coding rounds at Indian product companies are a different skill from DSA rounds. You get 45 to 90 minutes, a blank editor, and a spec like "build a star rating" or "implement debounce". Nobody wants the cleverest answer. They want working code, clean structure, and edge cases you thought of before they asked.After looking at a lot of these problems, I noticed the same few patterns come up again and again. If you only have a weekend, practice these five first. For each one I'll show a sol

I built Fitz: A 100% free, in-browser 3D device mockup studio (No subscription, 4K exports)

Every time I wanted to create a clean, photorealistic 3D mockup of a website or app for a pitch deck, client presentation, or Twitter post, I kept hitting the same frustrating wall:Every tool on the internet has become a subscription trap. Either they want $19/month, or they limit exports to blurry 720p, or they slap a huge watermark right across your design.So I sat down and built Fitz. ⚡ What is Fitz?Fitz Studio is an instant, in-browser 3D Apple device mockup and screenshot studio. It is