https://localpapa.com/blog/ Dev logs & tool guides from LocalPapa — privacy-first browser tools. en https://localpapa.com/blog/about.html https://localpapa.com/blog/about.html 24 Jun 2026 00:00:00 GMT LocalPapa Notes is the official blog behind LocalPapa — sharing tool guides, privacy-first design thinking, and our development journey in public. https://localpapa.com/blog/building-gimbal-los-measurement.html https://localpapa.com/blog/building-gimbal-los-measurement.html 24 Jul 2026 00:00:00 GMT The eighteenth dev-log post. Our gimbal motor sizing calculator works backward from a LOS stability target — but how do you actually measure that target in the real world? A survey of three optical measurement architectures with supporting literature, plus a minimal practical rig for small-to-mid gimbals. https://localpapa.com/blog/building-stock-dca.html https://localpapa.com/blog/building-stock-dca.html 30 Jun 2026 00:00:00 GMT The latest post in our dev-log series. Dollar-cost averaging (DCA) is the most common investment approach in Taiwan — but most calculators send your numbers to a server. We turned it into a fully local, multi-scenario compound-growth simulator. https://localpapa.com/blog/building-lottery.html https://localpapa.com/blog/building-lottery.html 25 Jun 2026 00:00:00 GMT The sixteenth dev-log. Lottery draws are independent random events — they can't be predicted. So what does "prediction" mean in a lottery predictor tool? Time-seeded LCG, deterministic numbers per 30-minute block, rolling ball animations — and why "prediction" is a meaningful SEO label but requires immediate honest clarification to the user. https://localpapa.com/blog/building-ziwei-interpretation.html https://localpapa.com/blog/building-ziwei-interpretation.html 25 Jun 2026 00:00:00 GMT The fifteenth dev-log. Placing stars is one thing; reading the chart is another. We evaluated three interpretation paths (local lookup, server-side AI, local + user's own AI), designed "star essence × palace domain" combinatorial lookup to avoid 168 hardcoded entries, and turned Three Directions/Four Alignments into a cross-service reusable deep-reading pattern. https://localpapa.com/blog/building-yizhang.html https://localpapa.com/blog/building-yizhang.html 25 Jun 2026 00:00:00 GMT The fourteenth dev-log. The architectural decision for Da Mo Yi Zhang Jing was settled before the first line: copy Zi Wei Dou Shu's three-layer architecture wholesale, not start from scratch. DRY lunar reuse, mod12 chart layout, six-path root nature, school settings, annual fortune — one divination service that deepened quickly from MVP. https://localpapa.com/blog/building-ziwei-doushu.html https://localpapa.com/blog/building-ziwei-doushu.html 24 Jun 2026 00:00:00 GMT The thirteenth dev-log. Zi Wei Dou Shu is one of the most complex Chinese metaphysical systems. We built a fully local chart engine — solar-to-lunar conversion, Ming Gong stem calculation, Five-Element Bureau from nayin, and the ancient Purple Star placement algorithm — all running in the browser, uploading nothing. https://localpapa.com/blog/building-okf-knowledge-pack.html https://localpapa.com/blog/building-okf-knowledge-pack.html 24 Jun 2026 00:00:00 GMT The twelfth dev-log post. An AI agent shouldn't have to parse ad- and layout-cluttered HTML to understand your site. How one generator turns the whole tool catalog into a clean, interconnected OKF knowledge pack and llms.txt. https://localpapa.com/blog/building-camera-tools.html https://localpapa.com/blog/building-camera-tools.html 24 Jun 2026 00:00:00 GMT The eleventh dev-log post. The camera is the third hardware the browser reads directly, after motion sensors and the microphone. How we built a QR scanner and a digital magnifier with it — and kept every frame on your device. https://localpapa.com/blog/building-audio-tools.html https://localpapa.com/blog/building-audio-tools.html 24 Jun 2026 00:00:00 GMT The tenth dev-log post. One microphone plus the Web Audio API yields tuning, noise metering, click tracks and live voice changing — powered by autocorrelation pitch detection, audio-clock scheduling and a real-time pitch-shift algorithm. https://localpapa.com/blog/building-offline-pwa.html https://localpapa.com/blog/building-offline-pwa.html 24 Jun 2026 00:00:00 GMT The ninth dev-log post. How does the second visit open instantly, even offline? How we used "self-hosting + a layered Service Worker cache" to cut CDN dependence — without stuffing a 30MB wasm into the repo. https://localpapa.com/blog/building-mermaid-editor.html https://localpapa.com/blog/building-mermaid-editor.html 24 Jun 2026 00:00:00 GMT The eighth dev-log post. LLMs spit out Mermaid text you can't actually see. Here's how we render it live in the browser, fight race conditions, export faithfully, and squeeze a whole diagram into a single share link. https://localpapa.com/blog/building-sensor-streaming.html https://localpapa.com/blog/building-sensor-streaming.html 24 Jun 2026 00:00:00 GMT The seventh dev-log post. From "viewing sensors on the phone" to "streaming the data live to a computer" — WebSocket, HTTP POST, Web Serial (USB), and how we tackled the maddening Mixed Content problem. https://localpapa.com/blog/building-phone-sensors.html https://localpapa.com/blog/building-phone-sensors.html 24 Jun 2026 00:00:00 GMT The sixth dev-log post. Level, compass, G-meter, shake detection — how we turned a phone's accelerometer and gyroscope into a live dashboard using only native browser APIs, with data that never leaves the device. https://localpapa.com/blog/building-sustainable-with-ads.html https://localpapa.com/blog/building-sustainable-with-ads.html 24 Jun 2026 00:00:00 GMT The fifth dev-log post. Free tools still rack up bills for domains, hosting and databases. Here's how we added ads — and got the compliance right — without betraying the "files never leave your device" promise. https://localpapa.com/blog/building-spa-to-multipage.html https://localpapa.com/blog/building-spa-to-multipage.html 24 Jun 2026 00:00:00 GMT The fourth dev-log post. LocalPapa was once a slick single-page app that almost nobody could find. Here's how we rebuilt it into a multi-page site so every tool gets its own landing page and organic traffic. https://localpapa.com/blog/building-pdf-toolkit.html https://localpapa.com/blog/building-pdf-toolkit.html 24 Jun 2026 00:00:00 GMT The third dev-log post. Rotate, PDF-to-image, unlock, image-to-PDF — how we brought advanced PDF operations into the browser with just pdf-lib, pdf.js and JSZip, without ever uploading a file. https://localpapa.com/blog/building-dori-calculator.html https://localpapa.com/blog/building-dori-calculator.html 24 Jun 2026 00:00:00 GMT The second post in our dev-log series. Security engineers hand-calculate DORI distances over and over — so we turned it into an instant, browser-local visual tool. https://localpapa.com/blog/building-pdf-to-markdown.html https://localpapa.com/blog/building-pdf-to-markdown.html 24 Jun 2026 00:00:00 GMT The very first tool in our dev log. How we reconstruct structured Markdown from a PDF's text coordinates — entirely in the browser, with zero uploads.