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QR codes look like magic — a grid of black and white squares that encodes anything from a URL to a business card. But how do they actually work? I decided to find out the hard way: implement the full QR Code Model 2 algorithm in vanilla JavaScript, zero external dependencies. The result: QR Code Generator — a free, client-side tool that generates QR codes from any text or URL. 👉 https://qr-code-generator-e83.pages.dev Why No Libraries? I maintain a collection of browser-only developer tools at devnestio . Every tool has the same rule: zero external dependencies. No npm installs, no CDN scripts, no servers. For most tools (JSON diff, Base64 encoder, UUID generator) that's easy. QR codes are different. The spec is a 126-page ISO document. Most developers just npm install qrcode and call it a day. But writing it from scratch taught me more about error-correcting codes, Galois field arithmetic, and matrix encoding than I ever expected. Worth every hour. What the Tool Does Real-time generation as you type (debounced at 80ms) Size selector — 128 × 128, 256 × 256, or 512 × 512 pixels Error correction level — L (7%), M (15%), Q (25%), H (30%) Color picker — any foreground and background color PNG download via canvas SVG download with crisp vector output at any scale How QR Codes Actually Work QR Code Model 2 (the standard you see everywhere) has six major steps. Here's the short version: 1. Data Encoding Text gets encoded into one of three modes based on content: Numeric ( 0-9 ): packs 3 digits into 10 bits — most compact Alphanumeric ( 0-9 A-Z $%*+-./:space ): 2 chars into 11 bits Byte (everything else): UTF-8, one byte per 8 bits The encoder picks the mode automatically and finds the minimum QR version (1–40) that fits the data. function detectMode ( text ) { if ( /^ \d +$/ . test ( text )) return NUMERIC_MODE ; if ( text . split ( '' ). every ( c => ALPHANUMS . includes ( c ))) return ALPHANUM_MODE ; return BYTE_MODE ; } 2. Reed-Solomon Error Correction This is the hard

The question My son was on the sofa with his iPad, poking at the live "Predict the Bracket" game — the whole 2026 World Cup knockout tree on one screen, every slot already filled with the crowd's favourite for that match. Tap a match, see who most people think goes through, watch the picks flow all the way up to a predicted champion. He frowned at it. "Daddy, how do they know which team plays which team? The teams aren't even decided yet." He'd caught something real. The little cards sitting in those slots were only predictions — the crowd's best hunch — but the shape underneath them, who-plays-who and where, was already locked in. Months before a single match kicks off. Fair question. The 2026 World Cup has 48 teams in 12 groups (A through L). The top two of every group go through — that's 24 teams. Then, to round it up to a nice bracket of 32, they also take the 8 best third-placed teams . Twelve groups, but only eight of their third-place teams get a golden ticket. "So you don't know which eight until the very end," he said. "But the bracket's already sitting right there on the screen." "Right." "That's cheating." It isn't cheating. It's one of the prettiest little bits of planning in all of sport, and by the end of the afternoon he understood it better than most adults do. We did it with the dining chairs. The setup, first Before the chairs, my son needed to know where these kids even come from. So we did the boring-but-important part first. A football group is a handful of teams who all play each other. When it's done, the best go forward, the worst go home, and — this is the bit that matters — there's a kid right on the line: the best of the rest , neither safely through nor clearly out. That borderline kid is the star of this whole story. Call them a wandering kid . To learn the trick, let's make the groups nice and small: two groups, A and B, three kids in each — six kids total. In each group the top kid goes straight through to the next round, the bottom ki

The document hub, our vision of DocuShark . We want to make collaboration simple again. There are too many amazing tools, too many surfaces to get lost in. Bring them together - and you've got a near-endless wealth of knowledge for anyone with access. The editor is out, and loaded with features, only getting more powerful. Our editor offers: high-speed, realtime collaborative editing on documents in your Cloud Workspace, documents that can write, draw, and store files at the same time, never lose access when your network goes out - offline copies let you use every feature anywhere, and agent endpoints (MCP) for all your agentic needs. The page and canvas are one, with generous file storage, allowing you to design whitepaper-level PDFs in hours, not weeks, with every file, reference, and diagram within that document, all while offline with changes saving when you're back online. It's a mini Google Drive in each document, with offline storage so you can edit anywhere, anytime with changes syncing across your team. The Integrations Story - Combine, don't Compete DocuShark isn't here to compete, it's here to integrate, and keep complex ideas lean and organized across platforms. As we release our integrations, knowledge drift shrinks, leaving you with richer context while you keep working with your favorite apps - or don't, we have rich editor tools as well. An Agent Powerhouse - Keep your Context Close DocuShark is built for agents from the ground up. Citations keep your agent's research properly attributed. Fields eliminate drift and block duplication before it starts. Anchored edits make changes surgical, not sweeping. More is in the works, and the roadmap is moving fast. Try DocuShark - The Editor's Free and Fast You can either launch straight into the editor , or get a cloud workspace and start collaborating today!

Everyone hits the same wall with Claude Code. You add a rule to CLAUDE.md . It works. You add ten more. They mostly work. You add forty more — and now Claude is cheerfully ignoring the rule you care about most, the one that's been sitting there since day one. So you make it LOUDER , in caps, with three exclamation points. It still gets skipped. The instinct is to write more. The fix is almost always to write less . Here's why, and what to do instead. Instruction-following has a budget, and you're overdrawn This is the part most CLAUDE.md guides skip. Frontier models reliably follow on the order of 150–200 instructions at once — and adherence to any single rule drops as you stack more on top of it. It isn't a cliff; it's a slow tax. Every line you add makes every other line a little less likely to be honored. Now subtract what you don't control: Claude Code's own system prompt already spends a chunk of that budget before your file is even read. So the working budget for your project rules is smaller than the headline number — and a sprawling 300-line CLAUDE.md isn't 300 rules followed, it's maybe the first 150 followed well and the rest treated as ambience. The mental model that fixes everything downstream: CLAUDE.md is a budget, not a wishlist. You are not writing documentation. You are spending a scarce attention allowance, and every line competes with every other line. The test for every line: would you bet $5 it's followed? Go through your file line by line and ask one question of each rule: would I bet money this fires every time it's relevant? Three outcomes: Yes, and it's load-bearing — keep it. This is what the budget is for. Nice to have, but I wouldn't bet on it — cut it, or move it to a referenced file (below). It's diluting the rules you would bet on. It absolutely must happen every time — then it doesn't belong in CLAUDE.md at all. Make it a hook. That third category is the one people get wrong, so let's be concrete about it. Advisory vs. deterministic:

A checkout saga spans inventory, payment, shipping, and loyalty. Downstream latency shifts every hour. Black Friday is not the day to discover your payment step timeout is baked into application.yml across twelve Spring Boot services. Kiponos.io gives every saga participant the same live orchestration parameters — step timeouts, retry budgets, compensation triggers — via one shared config tree. Each JVM reads locally on every saga step; ops adjusts once in the dashboard; WebSocket deltas propagate without redeploying the fleet. Why sagas break with static config Typical saga coordinator code: if ( step . elapsedMs () > 8000 ) { compensate ( "payment" , sagaId ); } That 8000 usually comes from: Per-service YAML — payment service says 8s, inventory says 12s; nobody agrees during an incident Env vars in Helm — change means rolling twelve deployments Shared DB config table — poll per step adds latency and coupling Saga steps are high-frequency reads inside workflow engines. You need local memory reads and async updates — the same contract as live API rate limits . Architecture: one tree, many participants ┌─────────────────┐ WebSocket deltas ┌──────────────────────┐ │ Kiponos.io UI │ ────────────────────────► │ Inventory service │ │ platform ops │ │ Payment service │ └─────────────────┘ │ Shipping service │ │ (each: in-mem SDK) │ └──────────┬───────────┘ │ .getInt() local ▼ ┌──────────────────────┐ │ saga step executor │ └──────────────────────┘ Every participant connects to profile ['orders']['v2']['prod']['sagas'] . When NOC extends payment.step_timeout_ms , all JVMs see the new value on the next step — no config server poll, no inter-service "what is timeout now?" REST calls. Shared saga config tree sagas/ checkout/ payment/ step_timeout_ms : 8000 max_retries : 2 retry_backoff_ms : 500 compensate_on_timeout : true inventory/ step_timeout_ms : 5000 max_retries : 3 hold_ttl_seconds : 120 shipping/ step_timeout_ms : 12000 fallback_carrier : ups_ground global/ saga_ttl_m

I've been building agent workflows for a while, and one capability keeps coming up that the ecosystem hasn't fully reckoned with: letting an AI agent publish a document to the public internet and hand someone a link. It sounds trivial ("save HTML, return a URL"). It isn't. The moment an autonomous agent can mint a public link, you've handed it a primitive that touches access control, data exposure, and reputation. This post is about the design questions that surface once you take that seriously, written by someone who builds in this space. Disclosure up front: I work on Thryvate, a document-sharing tool with an MCP server. More on that at the end, but the problems below are general. The naive version The first version everyone writes is a tool that takes content and dumps it to object storage behind a public CDN URL: publish(html) -> https://cdn.example.com/a8f3c2.html Ship that and an agent can now share its work. It can also now: expose a half-finished draft to anyone who guesses the URL, leave that URL live forever with no way to pull it back, publish something containing a customer's name with zero record of who saw it. For a human hitting "publish" deliberately, those are acceptable defaults. For an agent doing it as one step in a longer plan, they're landmines. What "publish" should actually mean for an agent A few properties turn the naive primitive into something you'd trust an agent to call: 1. Default to private, opt into public. The safe default for an agent-minted link is not "world-readable." It's "only people on this list" or "only people with the password." Public should be an explicit parameter someone has to set, not the fallback. 2. Revocability. Anything an agent publishes, you must be able to un-publish instantly. A live link is a liability with a half-life, and the ability to revoke is what makes it safe to let the agent create them liberally. 3. Expiry as a first-class field. "This link dies in 7 days" should be a parameter on the publish call,

The lawsuit dates back to a deadly incident in Arizona in 2023.

Apple is looking to alleviate some of the pressure on its supply chain by seeking an exception from the Trump administration to buy RAM chips from CXMT, a company blacklisted by the Pentagon over ties to the People's Liberation Army, according to the Financial Times. The skyrocketing prices of RAM and storage have driven Apple […]

AI can now scan major open-source projects and surface a batch of real, exploitable vulnerabilities in a single pass. That's a defensive win — until you remember attackers have the same tools. Anthropic, Google, Microsoft, OpenAI, AWS, and 15 other organizations aren't waiting for that race to get worse. On Thursday they launched Akrites under the Linux Foundation — a coordinated body built specifically for AI-era vulnerability discovery, remediation, and disclosure in critical open-source software. What actually changed A shared Security Incident Response Team (SIRT) replaces the fragmented model where multiple orgs independently scan the same libraries, file duplicate CVEs, and bury maintainers in noise Patch first, publish second — findings are held under strict confidentiality until a fix is ready and tested Fallback maintainer coverage — if a project has no active maintainer, Akrites steps in so fixes still reach downstream users Funded by Alpha-Omega , an OpenSSF project with $7M+ annual budget backed by the same founding members Three membership tiers — Premier (critical infra operators), General (contributing orgs), Associate (OSS foundations, free) The name comes from the Akritai — Byzantine soldiers who guarded the empire's outermost borders. The places most exposed, most frequently attacked, and most dependent on whoever showed up to defend them. The problem it's actually solving The current coordinated disclosure model was designed around a world where finding vulnerabilities took weeks of expert work. AI has collapsed that timeline. Endor Labs CEO Varun Badhwar put a number on it: thousands of validated open-source vulns surfaced by AI in recent months, with fewer than 5% patched. And the old model makes it worse — every org independently sitting on knowledge of an unpatched flaw is another leak risk before a fix exists. "For years, we have believed finding vulnerabilities was never the hard part. Fixing them was. AI has made that gap impossible to igno

Back in May we here at Waggy Labs launched the beta release of our Web Component UI kit " Yumekit ". Yumekit is a pure web component UI toolkit. Upon its release, it was comprised of roughly 36 fully styled and fully functional UI components that work with just about every web architecture straight out of the box. No configuration or setup necessary, all one needs to do is include the Yumekit script (using either a CDN or installed through NPM) and start building. All components come styled out of the box with no need to include any style sheets. Last week, we launched version 0.5. With this latest release, that job is being made easier with the inclusion of new components that add several layout options as well as new Data, Navigation, and Utility components, bringing the total number of components to 51. For us, this toolkit has provided us a framework-agnostic solution for our internal tools as well as any client projects. With over 60 themes spread over 9 well-known (and some brand new) open source Design Systems all built directly into the library, we have plenty of options available to us to keep our designs fresh without needing to spend hours dealing with CSS. It's light-weight, dependency free, and well documented. New in 0.5 Animate The y-animate component allows you to animate entrances and exits for nested components using a few simple configuration attributes. Code The y-code component allows you to display formatted and colorized code, as well as providing a few easy and convenient ways for your users to copy the provided code. Help The y-help component provides a tutorial experience for users of your application with minimal configuration. Simply provide the elements to be highlighted, the messages to be shown, and it handles the rest! Paginator y-paginator provides a configurable set of pagination buttons to help your users navigate through large data sets. Sidebar We had originally included a y-appbar component (which we still do) that had a "Sideba

Your AI is making your content invisible. Not because it writes badly. Because it writes safely . Ask ChatGPT to summarize an article and it will produce a polished, agreeable précis that offends nobody and surprises nobody. The output is technically accurate and completely forgettable. The problem is structural: most people prompt their AI to confirm what an article says, not to find where it fights with the crowd . The result is a feed full of content that agrees with other content, in increasingly fluent prose, at exponentially increasing volume. If you want to be read, you need to stop prompting for summaries and start prompting for conflict. Why Agreement Is the Fastest Path to Obscurity There is a reliable body of research behind why contrarian content performs. Jonah Berger and Katherine Milkman's widely cited study, "What Makes Online Content Viral?" ( Journal of Marketing Research , 2012) , found that content evoking high-arousal emotions — anger, awe, anxiety — is significantly more likely to be shared than content that merely informs or reassures. Agreement is a low-arousal state. Surprise and contradiction are not. This is not a trick to manufacture outrage. It is a structural observation: the human brain is wired to pay attention to pattern breaks. An article that says "AI is changing content creation" registers as noise. An article that says "AI is making content creation worse, and here's the data" registers as a signal worth attending to. The distinction matters because the mechanism is cognitive, not emotional. You are not trying to provoke readers. You are trying to interrupt the predictive pattern they've built from reading a hundred similar articles before yours. The Problem With Generic AI Summarization When you ask an LLM to "summarize this article" or "give me the key takeaways," the model optimizes for coverage and balance. It is trained on human feedback that rewards thoroughness and penalizes controversy. The output tends to be accurate, ne

Imagine this - you rely on data that you download every day from some system to your own. That requires a trip to the server asking for information, and then a trip back with the payload we requested. This seems pretty fast since the internet is fast. But we also know the programming concept DRY (Don't Repeat Yourself). So, can we apply this principle to how we handle the scenario described above, creating something like DRD (Don't Repeat Data)? Well, yes. There is something to handle this, and it's called — Zero Copy . What is Zero Copy? As the name suggests, you are copying zero data, and yet, you are getting it on your system. How is this possible? If you think about it, you'll probably come to the conclusion that we are just opening a window. The data is just out there to be looked at by those who are allowed to. There's no need to bring the same data to different people's windows; we're just keeping the data in one place and making it available to anyone who needs it. What does this mean for ServiceNow? When it comes to Operations Management—dealing with data fetched from different databases (like monitoring data from Datadog or Dynatrace, ERP data from SAP or Workday, or cloud platforms like Snowflake, AWS, or Azure)—copying that data has traditionally been a hassle. We were reliant on sometimes complex ETL (Extract, Transform, Load) pipelines or massive data extracts. This complicated the whole process, consumed a lot of time, and required careful checking of data pre- and post-migration. So how exactly does Zero Copy help us here? Virtual Data Fabric Tables. Instead of copying data extracted from other tools, ServiceNow queries the exact data that is requested. It temporarily holds that data in memory for the user to interact with. During that time, the user can leverage that data for various use cases as required—and once they are done, it's gone. So, what exactly are the benefits of Zero Copy?! No need for data duplication on the destination. No need for d

The Knowledge Atom: Writing for Machines That Read The Hoarder's Reflex Everyone is learning to feed the machine. Bigger context files. Paste the whole document. "Give the AI all the context it needs." The entire industry has converged on a single instinct: when in doubt, add more. It's the wrong instinct. A context window is not a hard drive. It's a desk. And a desk piled with every document you own is not a well-informed desk — it's an unusable one. The model doesn't read better because you gave it more. It reads worse, because the one line that mattered is now buried under a thousand that didn't. Knowledge an AI can't find is knowledge it doesn't have. Knowledge it always carries is weight it always pays. The Two Failures There are only two ways to get this wrong, and almost everyone commits one of them. The first is the dump . You take everything you know and pour it inline — into the system prompt, the master config, the one document to rule them all. It feels thorough. It is the opposite. Every token you add dilutes every token already there. Signal drowns in completeness. The model now has all the knowledge and none of the focus. The second is the orphan . You did the disciplined thing. You wrote a clean, perfect note, in its own file, out of the way. And then nothing pointed to it. No index, no trigger, no path back. The note is immaculate and invisible — which is worse than never writing it, because you believe the knowledge is in the system when in fact it is dead. Both failures share one root: confusing having knowledge with retrieving it. Same Pattern, New Sauce Watch the field long enough and you'll see the same thing return, repainted each time. The "Ralph Wiggum" loop becomes "the agentic loop." Agent teams that talk to each other become a single orchestrator, and then an agent that makes other agents talk to each other. Every cycle sells itself as the breakthrough. Every cycle is a re-skin of the last. Underneath the churn, only one thing actually ch

A full-stack, peer-to-peer coinflip betting game on Solana A full-stack, peer-to-peer coinflip betting game on Solana. Players connect a wallet, create or join on-chain game rooms, and compete head-to-head for 2× the stake. The UI updates in real time over WebSockets, outcomes are resolved on-chain with Orao VRF, and the backend tracks rooms, chat, and match history in MongoDB. I open-sourced coinflip-casino for developers in Solana / Anchor smart contract development . This post walks through what it does, how the pieces fit together, and how to run it locally. Live demo / site: https://www.flip.is/ Why I built this Learn full-stack Web3 game architecture (wallet + program + backend + UI) Study provably fair randomness with on-chain VRF integration Fork and customize a peer-to-peer on-chain betting room model Most tutorials stop at a smart contract or a UI mockup. I wanted a complete vertical slice — wallet flow, on-chain logic, backend state, and a responsive frontend — so you can study or fork a production-shaped codebase. What it does Create a room — Pick Head or Tail, set bet amount, choose SOL or SPL token. Join a room — Browse open games in the live lobby and match against another player. PvP coinflip — When two players are in the same room, the backend triggers on-chain resolution. 2× payout — The winner receives double the bet (fees apply on-chain). Room expiration — Open rooms older than 5 minutes with no opponent are expired and refunded automatically. Portfolio stats — Win count and total games per wallet. Wallet connect — players sign in with a Solana wallet Peer-to-peer rooms — create or join head-to-head matches Architecture at a glance Wallet layer — users connect a Web3 wallet to sign transactions On-chain program — Anchor/Rust logic for escrow, rooms, and settlement Randomness — verifiable flip outcomes via Orao VRF on Solana Real-time layer — WebSocket events push room and flip state to the UI Persistence — MongoDB stores rooms, chat, and historic

People complain that websites are all starting to look the same. They are not entirely wrong. A lot of modern websites do look alike. They have familiar navigation bars, predictable layouts, large hero sections, cards, and responsive grids. Buttons look like buttons. Forms look like forms. But, I would argue that's a good thing. Software is supposed to feel familiar. A website is not a painting. It is not a brand mood board. A website is usually a tool that someone is trying to use to accomplish something. They want to read, buy, search, compare, book, or solve a problem. And when people are trying to get something done, originality is not always a virtue. Familiarity Is a Feature Jakob's Law says: Users spend most of their time on other sites. This means that users prefer your site to work the same way as all the other sites they already know. Users do not arrive at your website as blank slates. They bring expectations from every other website and app they have used. They expect the logo to link home. They expect navigation to be near the top or side. They expect search to look like search. They expect account settings under an avatar or profile menu. They expect mobile navigation to collapse into a menu. When your site follows those expectations, users can spend their mental energy on the task instead of the interface. That is the point. Good design reduces cognitive load. It does not force users to relearn basic interaction patterns just because a company wanted to look different. Different Is Not Automatically Better There is a common mistake in web design: confusing distinctiveness with quality. A site can be visually unique and still be frustrating to use. It can win design awards while annoying the actual people who need to navigate it. Novelty has a cost. Every unusual layout, hidden interaction, custom scroll behavior, strange menu, or clever visual metaphor asks the user to stop and figure out what is going on. If you are building a portfolio, an art proje

nginx Event Loop — Complete Lifecycle Reference A precise, bottom-up reference covering every buffer, syscall, interrupt, and data movement from the moment a TCP packet hits the NIC to the moment a response is sent back. Two concurrent users are used throughout as a concrete example. Table of Contents Foundations — fd and Socket Hardware Layer — NIC, DMA, Interrupts Kernel Structures and All Buffers epoll — How the Worker Waits Efficiently nginx Startup Sequence Complete Request Lifecycle — Two Concurrent Users What Happens While Worker is Busy All Buffers — Master Reference All Syscalls — Master Reference Failure Modes 1. Foundations 1.1 Everything is a File Linux's core philosophy: every I/O resource — files on disk, network connections, pipes, terminals, devices — is represented as a file. This means one unified API ( read , write , close ) works on all of them. The kernel manages the actual resource. Your process holds a token. 1.2 File Descriptor (fd) A file descriptor is just an integer . It is a per-process token that refers to a kernel-managed resource. The kernel maintains a table per process called the fd table — a simple array where the index is the fd and the value is a pointer into the kernel. Process fd table: ┌─────┬───────────────────────────────┐ │ fd │ points to │ ├─────┼───────────────────────────────┤ │ 0 │ stdin │ │ 1 │ stdout │ │ 2 │ stderr │ │ 3 │ listen socket (nginx) │ │ 5 │ User A client connection │ │ 6 │ User B client connection │ │ 12 │ backend connection for User A │ │ 13 │ backend connection for User B │ └─────┴───────────────────────────────┘ 0, 1, 2 are always pre-assigned. Application fds start from 3 upward. The fd is meaningless on its own. It only means something when passed to a syscall — the kernel uses it to look up the real resource. 1.3 Socket A socket is the kernel's internal data structure representing one end of a network connection. Created when your process calls socket() . Lives entirely in kernel RAM. Your process nev

One of the hardest things about going freelance as a developer isn't writing code — it's knowing what to charge. Charge too little and you're basically doing a salaried job without the benefits. Charge too much without backing it up and you scare off clients. Most developers I've spoken to either guessed their rate or copied someone else's. Neither is a great strategy. In this article I want to walk you through exactly how to calculate your freelance day rate properly — based on real numbers, not gut feeling. Why Most Freelancers Get Their Rate Wrong The most common mistake is this: taking your old salary and dividing it by 260 working days. That ignores: Taxes (you now pay both sides of self-employment tax in the US) Unpaid days — holidays, sick days, slow months with no clients Business costs — software, hardware, insurance, accountant fees No employer pension or benefits — you fund all of this yourself If you were earning $80,000 as a salaried developer and you divide that by 260, you get roughly $307/day. But that's actually a pay cut once you factor everything in. The Right Formula Here's the framework: Step 1 — Work out your actual billable days A year has 260 working days. Subtract: Public holidays (~10 days in the US) Your own holiday allowance (~15 days) Estimated sick days (~5 days) Non-billable time: admin, chasing invoices, marketing yourself (~20 days) That leaves roughly 210 billable days. Step 2 — Calculate your real income target Take what you want to take home and gross it up for tax. If you want $70,000 net and your effective tax rate is around 30%, your gross target is roughly $100,000. Step 3 — Add your business costs Software subscriptions, hardware depreciation, liability insurance, accountant — easily $5,000–$10,000/year for a freelance developer. Step 4 — Divide by billable days $110,000 ÷ 210 = $524/day That's your minimum. Price below that and you're losing money compared to employment. A Faster Way — Use a Free Calculator If that maths mad

getComputedStyle(element).fontFamily returns the CSS declaration: "Hiragino Kaku Gothic ProN", "Yu Gothic", "Noto Sans JP", sans-serif . That's not the font that rendered. It's a priority list. The browser picks the first one that's available and contains a glyph for the character being rendered. For Latin text, this distinction usually doesn't matter — Windows, macOS, and Linux have converged on a small set of common system fonts. For Japanese, it matters enormously. The visual weight, stroke contrast, and letterform style of Hiragino, Yu Gothic, and Noto Sans JP are genuinely different. A site designed on macOS (where Hiragino is the system Japanese font) looks different on Windows (where Yu Gothic is the fallback). Here's how to figure out what's actually rendering, and what I learned building Japanese Font Finder to automate it. Why getComputedStyle Doesn't Answer the Question getComputedStyle(el).fontFamily gives you the cascade result — what the browser received after applying all CSS rules. But it doesn't tell you which entry in the stack was selected. The underlying question is: does this font exist on this system, and does it have a glyph for this specific character? For Japanese, both conditions matter. A font might exist on the system but only cover a subset of kanji (common with CJK fonts that split across multiple files). The browser will use that font for characters it covers, and fall back for others. Canvas-Based Font Detection The classical technique uses a <canvas> element to measure text rendered with each font in the stack: function getFallbackWidth ( canvas , char ) { const ctx = canvas . getContext ( ' 2d ' ); ctx . font = `16px monospace` ; // known-available baseline return ctx . measureText ( char ). width ; } function testFont ( fontName , char ) { const canvas = document . createElement ( ' canvas ' ); const ctx = canvas . getContext ( ' 2d ' ); ctx . font = `16px " ${ fontName } ", monospace` ; return ctx . measureText ( char ). width ; }

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Kai Wright is the co-host of Stateside with Kai and Carter over at the Guardian. But Wright has been bringing his unique insights to listeners for years. He's also hosted Notes From America, The United States of Anxiety, and Indivisible. He's a Peabody Award-winning journalist who has profiled powerful men, explored what it means to […]