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I Built a Scheme Compiler with AI in 4 Days

When does MCP make sense vs CLI?

Show HN: MCP Playground – free MCP test servers, inspector, and 10K+ server list MCP Playground is a Postman-style tool for MCP — inspect servers, execute tools live, test your client, all from the browser.<p>Four things in one place:<p>1. Free hosted MCP servers — four public test servers anyone can point their client at: Echo (connectivity), Auth (Bearer token flow), Error (error handling), Complex (multi-tool schemas).No sign-up, just use the URL.<p>2. Server inspector — paste any remote MCP server URL, see all its tools&#x2F;resources&#x2F;prompts, execute them live, inspect the full JSON-RPC log. HTTP, SSE, and WebSocket all supported.<p>3. Registry — 10,000+ servers indexed by category. Each links to the repo and can be tested in the inspector directly.<p>4. Recipes + guides — 45 articles and step-by-step workflows for real use cases: GitHub PR reviewer, standup bot, database query assistant, Meta ads automation, and more.<p>Everything free, no install, no sign-up.<p>Happy to answer questions on the implementation.

AI Made Writing Code Easier. It Made Being an Engineer Harder

Ape Coding

Show HN: I'm a teen from Kenya and I built a package manager in Rust for fun

Show HN: I built a browser-based 3D editor since I didn't want to learn Blender process demo - <a href="https:&#x2F;&#x2F;i.redd.it&#x2F;fbhlwsq1gcmg1.gif" rel="nofollow">https:&#x2F;&#x2F;i.redd.it&#x2F;fbhlwsq1gcmg1.gif</a> render demo - <a href="https:&#x2F;&#x2F;i.redd.it&#x2F;smddwtryhcmg1.gif" rel="nofollow">https:&#x2F;&#x2F;i.redd.it&#x2F;smddwtryhcmg1.gif</a><p>I love making creative software. I spent a few years making pixel art software but recently have gotten into 3d animation and 2d animation and really wanted a way to realize crazy ideas.<p>Blockbench didn&#x27;t feel quite right, spline is super well made but felt catered too much to just idle website animations, and I really didn&#x27;t want to fall down a master class in Blender just to make some silly stuff. While I&#x27;m definitely not discounting Blender&#x27;s literal powerhouse functionality, I wanted something smaller, easier to adopt, and something directly inside the web ecosystem. So that when I want to make assets for silly games I won&#x27;t have to jump through any hoops to make everything match up and render nicely. So, I made Topomaker (tentative name).<p>It&#x27;s sporting your basic 3d modeling, coloring, and animation. It&#x27;s currently supporting exports to mp4&#x27;s and gifs for sharing, and then glb&#x27;s and obj&#x27;s for making games in threejs.<p>I literally just started it a couple weeks ago so there are probably tons of bugs, so maybe not for anything serious, but feel free to play around with it and let me know what you think!

Against Query Based Compilers

Show HN: I built a zero-browser, pure-JS typesetting engine for bit-perfect PDFs Hi HN, I&#x27;m a film director by trade, and I prefer writing my stories in plain text rather than using clunky screenplay software. Standard markup like Fountain doesn&#x27;t work for me because I write in mixed languages, so I use Markdown with a custom syntax I invented to resemble standard screenplay structures.<p>This workflow is great until I need to actually generate an industry-standard screenplay PDF. I got tired of manually copying and pasting my text back into the clunky software just to export it, so I decided to write a script to automate the process. That&#x27;s when I hit a wall.<p>I tried using React-pdf and other high-level libraries, but they failed me on two fronts: true multilingual text shaping, and complex contextual pagination. Specifically, the strict screenplay requirement to automatically inject (MORE) at the bottom of a page and (CONT&#x27;D) at the top of the next page when a character&#x27;s dialogue is split across a page break.<p>You can&#x27;t really do that elegantly when the layout engine is a black box. So, I bypassed them and built my own typesetting engine from scratch.<p>VMPrint is a deterministic, zero-browser layout VM written in pure TypeScript. It abandons the DOM entirely. It loads OpenType fonts, runs grapheme-accurate text segmentation (Intl.Segmenter), calculates interval-arithmetic spatial boundaries for text wrapping, and outputs a flat array of absolute coordinates.<p>Some stats:<p>Zero dependencies on Node.js APIs or the DOM (runs in Cloudflare Workers, Lambda, browser).<p>88 KiB core packed.<p>Performance: On a Snapdragon Elite ARM chip, the engine&#x27;s &quot;God Fixture&quot; (8 pages of mixed CJK, Arabic RTL, drop caps, and multi-page spanning tables) completes layout and rendering in ~28ms.<p>The repo also includes draft2final, the CLI tool I built to convert Markdown into publication-grade PDFs (including the screenplay flavor) using this engine.<p>This is my first open-source launch. The manuscript is still waiting, but the engine shipped instead. I’d love to hear your thoughts, answer any questions about the math or the architecture, and see if anyone else finds this useful!<p>--- A note on AI usage: To be fully transparent about how this was built, I engineered the core concept (an all-flat, morphable box-based system inspired by game engines, applied to page layouts), the interval-arithmetic math, the grapheme segmentation, and the layout logic entirely by hand. I did use AI as a coding assistant at the functional level, but the overall software architecture, component structures, and APIs were meticulously designed by me.<p>For a little background: I’ve been a professional systems engineer since 1992. I’ve worked as a senior system architect for several Fortune 500 companies and currently serve as Chief Scientist at a major telecom infrastructure provider. I also created one of the world&#x27;s first real-time video encoding technologies for low-power mobile phones (in the pre-smartphone era). I&#x27;m no stranger to deep tech, and a deterministic layout VM is exactly the kind of strict, math-heavy system that simply cannot be effectively constructed with a few lines of AI prompts.

Ghostty – Terminal Emulator

A set of ready to use Agent Skills for research, science, engineering, analysis, finance and writing.

Show HN: Vertex.js – A 1kloc SPA Framework Vertex is a 1kloc SPA framework containing everything you need from React, Ractive-Load and jQuery while still being jQuery-compatible.<p>vertex.js is a single, self-contained file with no build step and no dependencies.<p>Also exhibits the curious quality of being faster than over a decade of engineering at Facebook in some cases: <a href="https:&#x2F;&#x2F;files.catbox.moe&#x2F;sqei0d.png" rel="nofollow">https:&#x2F;&#x2F;files.catbox.moe&#x2F;sqei0d.png</a>

Show HN: Rust compiler in PHP emitting x86-64 executables

Show HN: Terminal-Style Portfolio on the Internet Posted about this last year, since then learned a lot, changed a lot and can still say it&#x27;s the best Terminal-Style Portfolio Website on The Internet

Show HN: Effective Git As many of us shift from being software engineers to software managers, tracking changes the right way is growing more important.<p>It’s time to truly understand and master Git.

Decision trees – the unreasonable power of nested decision rules

Show HN: Built a tool that turns your GitHub commits into build-in-public posts I kept failing at building in public for the same reason every time: not fear of judgment, just the blank page after a long day of shipping.<p>Something always happened. But converting &quot;refactored auth flow&quot; or &quot;fixed that edge case that&#x27;s been annoying me for a week&quot; into something worth posting felt like a second job on top of the actual job. So I&#x27;d skip it. Then skip it again. Then stop entirely.<p>The approach: connect your GitHub, it pulls recent commits and repo activity, and generates draft posts for multiple platforms in your tone — raw founder voice, not content creator polish. The idea is you&#x27;re always starting from something real you actually did, not staring at a blank box trying to manufacture insight.<p>A few decisions I made consciously:<p>Didn&#x27;t want to build another scheduler. Hypefury&#x2F;Typefully solve distribution. This solves the upstream problem: knowing what to say in the first place.<p>Kept the output editable and minimal — 2-3 options per session, short, easy to tweak. Not trying to automate your voice, just unblock it. Free tier to start. Wanted real usage before charging anyone.<p>Still early. Roadmap includes better tone calibration, tighter commit parsing, and more platform targets. But I&#x27;ve been using it daily myself which is the real test. Would love feedback, especially from anyone who&#x27;s tried and failed at BIP consistency before.

WiFi DensePose turns commodity WiFi signals into real-time human pose estimation, vital sign monitoring, and presence detection — all without a single pixel of video.

Show HN: React-Kino – Cinematic scroll storytelling for React (1KB core) I built react-kino because I wanted Apple-style scroll experiences in React without pulling in GSAP (33KB for ScrollTrigger alone).<p>The core scroll engine is under 1KB gzipped. It uses CSS position: sticky with a spacer div for pinning — same technique as ScrollTrigger but with zero dependencies.<p>12 declarative components: Scene, Reveal, Parallax, Counter, TextReveal, CompareSlider, VideoScroll, HorizontalScroll, Progress, Marquee, StickyHeader.<p>SSR-safe, respects prefers-reduced-motion, works with Next.js App Router.<p>Demo: <a href="https:&#x2F;&#x2F;react-kino.dev" rel="nofollow">https:&#x2F;&#x2F;react-kino.dev</a> GitHub: <a href="https:&#x2F;&#x2F;github.com&#x2F;btahir&#x2F;react-kino" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;btahir&#x2F;react-kino</a> npm: npm install react-kino

Mount Mayhem at Netflix: Scaling Containers on Modern CPUs