R&D mechanical engineer with an aerospace background: product reliability, DVT, NPI and root-cause analysis.
On the side I build offline-first tools and AI experiments, and I'm learning Fortran for CFD work.
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Local-first No account, no server required. Most of what I ship keeps working offline. |
Real apps on every platform Desktop installers, Android and iPhone builds, and a live web demo you can try right now. |
Built like hardware Test suites run in CI on every push (badge above) and releases are versioned: verify before shipping, like a DVT build. |
Ranked by how solid each project is: test suites, shipped releases and downloads, a working live demo and commit history.
![]() Airiz Motor: USB jog, remote control and camera by code, live device checks and a camera-based wobble test. Live demo · Download · Landing page · 37 test files · README |
![]() Twin: Invest and day-trade with a twin that replays 10,000 futures before you risk real money. Live demo · Download · Landing page · 135 test files · README |
![]() Glow: Four AI apps on one free account, in 4 languages. No API keys, and it keeps working offline. Live demo · Download · Landing page · 26 test files · README |
![]() Buddy: Guides new factory engineers through PLM, SRM and ERP screens click by click, or clicks for them. Runs on local models and asks before risky actions. Download · Landing page · 11 test files · README |
![]() Datum Bench: NPI task flow, review checklists, an issue log and 11 engineering calculators in one place. Live demo · Download · Landing page · 11 test files · README |
![]() Mint: Synced on every device, with expenses you log by texting Mint on WhatsApp. Live demo · Download · Landing page · 8 test files · README |
![]() Vitals: Cleans storage you can undo, forecasts battery wear and finds what drains your device. Live demo · Download · Landing page · 6 test files · README |
![]() EarlyStar: Find GitHub repos before they trend, ranked by the stars they actually gained, with real activity next to the hype. Live demo · Download · Landing page · 4 test files · README |
Where the day job meets the side projects: CAD automation, CFD studies, a factory battery check and the small tools I use in R&D.
![]() Datum CAD: A PRD plus six reference photos becomes a validated STEP solid, with an STL preview. Landing page · README |
![]() Explicit MacCormack Method: A computational fluid dynamics study of a predictor-corrector scheme, with plotted results. Landing page · README |
![]() Upwind Differencing Scheme: A computational fluid dynamics study of upwind differencing, with plotted results. Landing page · README |
![]() Peakwise: A neutral 60-second check of whether a battery pays back for a Taiwan factory, with the real Taipower tariff, the MOEA subsidy and a quote checker. Live site · README |
2 workplace automations: small tools I use in the R&D day job
- PLM AML Approval
: Python and Playwright tool that walks a Windchill-based PLM part-approval (AML) workflow end to end, verifies every field and stops before Submit so a person makes the final check.
Landing page · README - Outlook Archiver
: A small Windows daemon that keeps Outlook's Inbox and Sent Items empty by moving every message into an Archives PST, while logging each one and showing a desktop toast so nothing is missed.
Landing page · README
32 projects in progress, ranked by how solid they are, then potential
Ranked by how solid each project is (tests, releases, a working demo), then by potential. Activity refreshes automatically every 2 hours.
- Sync
: Listen to music together in real time from anywhere, with Spotify, Apple Music, YouTube and shared files in one room, plus voice chat that lowers the music.
Landing page · README · Updated Nov 4 · 2 commits this week - Together
: A private life plan for couples, from dating to retirement: a shared roadmap with both ages at every milestone, goals, savings and a monthly check-in. End-to-end encrypted, works offline. Try the demo.
README · Updated Nov 6 · 16 commits this week - Guang Yao Together 光耀同行
: An unofficial Traditional Chinese learning app with admin-published lessons, an AI study companion, spaced review and streaks. A PWA, an Android app and a free iPhone home-screen app.
Landing page · README · Updated Nov 5 · 3 commits this week - Peers
: Verified reviews across category modes (food, travel, market, AI tools, health, finance). Every category shares one interface, with a built-in Use it / Wait / Skip scorecard.
Landing page · README · Updated Nov 5 · 2 commits this week - Atomize
: AI content repurposing SaaS. Paste one blog post, get 5 LinkedIn posts, 8 tweets, 3 newsletters and a YouTube Short script. Next.js 14 + Claude, Lemon Squeezy for payments.
Landing page · README · Updated Nov 5 · 6 commits this week - Haru
: A cozy photo diary and walking map: each day becomes a card with a tiny diorama lit by that day's weather. English, Japanese and Korean; runs in the browser, with Android, Windows and Mac downloads.
Landing page · README · Updated Nov 5 · 6 commits this week - Lingua
: Floats live translated captions over Microsoft Teams by reading the caption strip and translating it as people speak.
Landing page · README · Updated Oct 28 · quiet this week - Fade
: A barber marketplace built on short videos: find a barber from a 15-second cut, then book, pay and tip them directly. Serverless on Nostr relays, 0% platform fee.
Landing page · README · Updated Oct 30 · quiet this week - Sweep
: The
/sweeppipeline: validate an idea, then sync the repo to GitHub and mirror a note to Obsidian. PowerShell helper plus an OpenCode slash command.
Landing page · README · Updated Nov 4 · 2 commits this week - Nudge
: Reads your own Instagram, WhatsApp, Telegram and iMessage exports to show who you have left on read, with a ready-to-send opener. Weekly digest, iOS widget, fully local.
Landing page · README · Updated Nov 4 · 11 commits this week - Cairn
: A second brain that lives inside your repo: capture, brainstorm on an ideas wall, log decisions and move tasks, all as plain Markdown next to the code. Turns code TODOs into tasks and writes a context brief for AI assistants. Works with Obsidian; zero dependencies. Try the demo.
Landing page · README · Updated Nov 6 · 12 commits this week - Hazel
: One creator studio, three apps: Hazel Shorts for faceless explainer shorts, Hazel Sped for sped-up and mashup edits of your songs, and Hazel Long to create, cut and publish long-form video.
Landing page · README · Updated Nov 5 · 3 commits this week - Pips
: Desktop pet and Pomodoro widget for Windows: 51 animated animals, skill battles, minigames, live weather and 4 languages.
Landing page · README · Updated Nov 5 · 15 commits this week - Orbis
: Communication, identity and protection in one app, plus Orbis Chat: real-time messaging with accounts, teams, email invites and push notifications on web, iPhone and Android.
Landing page · README · Updated Nov 5 · 2 commits this week - House of Articles
: Athlete-moment sneaker news plus a live market feed, linking on-court moments to resale price moves.
Landing page · README · Updated Nov 3 · 1 commit this week - Undanu
: Digital wedding invitations for Indonesia: personal WhatsApp links, RSVP and guest book, reminders and QR check-in on the day. Templates for every religion, Bahasa Indonesia and English, plain Python and SQLite.
Landing page · README · Updated Nov 4 · 19 commits this week - Jeda
: A quiet virtual space and living library for every faith in Indonesia: light incense or a candle, read teachings and rituals, track holy days and family memorials. Clergy-reviewed, works offline.
Landing page · README · Updated Nov 4 · 20 commits this week - Push Lab
: Two tools for mobile QA: Beacon is a self-hosted push server, and Tether puts your Android phone in the browser with scripted QA flows.
Landing page · README · Updated Nov 5 · 9 commits this week - The Morning Paper
: A morning newspaper for markets, AI, chips, robotics and space: merged stories with an AI brief and a "why it matters" line, plus a stock desk with live prices and alerts synced across devices.
Landing page · README · Updated Nov 6 · 65 commits this week - LinkedIn Autopilot
: Turns my GitHub into a LinkedIn schedule. Posts projects through the official API using only real README facts and live screenshots, never repeats itself, and learns from LinkedIn visitors, stars and "Try it" clicks which projects to post next.
README · Updated Nov 6 · 2 commits this week
Promising: early, with real potential (12)
- Steward
: An OpenAI-compatible proxy that keeps a customer-facing chatbot on task: redirects drift, blocks prompt injection and logs cost per feature. Python and TypeScript SDKs and a live playground.
Landing page · README · Updated Nov 5 · 7 commits this week - Rewind
: A community archive for old TV series missing from today's streaming services: memories, quotes, a personal shelf and where each show can still be watched.
Landing page · README · Updated Nov 2 · 1 commit this week - Teman Sehat
: A GERD and acne lifestyle companion in English and Bahasa Indonesia: reminders, an after-meal timer, a trigger log and a skin routine.
Landing page · README · Updated Nov 4 · 3 commits this week - Sortie
: A playful, fully undoable file organizer: files fly into their folders, deletes go into a recoverable bag, and an AI assistant proposes a plan you run or cancel.
Landing page · README · Updated Nov 5 · 3 commits this week - E-coder
: A stdlib-only coding agent that plans, edits files and runs commands behind a deny-list and fail-closed confirmation. Local Ollama by default; 67 hermetic tests, no third-party dependencies.
Landing page · README · Updated Nov 3 · 6 commits this week - CrewCup
: Office coffee for teams in Southeast Asia: one-tap usual orders and group runs paid from the company allowance, a café order board, HR budgets and rewards. EN / ID, plain Python and SQLite.
Landing page · README · Updated Nov 3 · 2 commits this week - shiphub
: Pinterest for app ideas: save ideas to boards, discuss and fork them, claim one with "I'm building this" and mark it shipped. GitHub sign-in, Python with SQLite or Postgres.
Landing page · README · Updated Nov 4 · 10 commits this week - LaunchKit
: Promote an app before it ships: a referral waitlist, reward emails, an AI build-in-public post writer, tracked links per signup and a launch-week checklist. Zero-dependency Python and SQLite.
Landing page · README · Updated Nov 4 · 7 commits this week - Signals
: A $0-capital crypto signal bot: RSI, MACD, ATR and EMA confluence alerts on 4h candles, with paper trading, a backtester and a risk-capped executor.
Landing page · README · Updated Nov 4 · 4 commits this week - SkillMouse
: Run your Claude Code, Codex and OpenCode skills on any selected text, straight from the mouse, with a local Ollama model or any OpenAI-compatible endpoint. Raycast-style launcher; Windows, single-file Python.
Landing page · README · Updated Nov 6 · 5 commits this week - Titian
: A broker-run B2B bridge for industrial manufacturers in Southeast Asia: 3D catalogs, RFQ baskets and a supplier portal, with every introduction screened. Built on Respark.
Landing page · README · Updated Nov 5 · 4 commits this week - KiniBuka
: Find small Indonesian UMKM stalls that are open right now: a live feed of openings, closings, promos and bazaars, a map with search, follow alerts, and order-ahead with a one-tap WhatsApp handoff.
Landing page · README · Updated Nov 5 · 3 commits this week
22 tools in juw12/tools: small, local and private, Python standard library only
No accounts and every tool ships with a self-test. See the landing page or README; scaffold a new one with python3 toolbox.py new <name>.
- Subscription Leak Finder: Reads your bank CSV and finds hidden recurring charges, quiet price rises, trials that turned paid and overlapping services.
Demo:python3 toolbox.py demo subscription_leaks - Bank Fee Detector: Finds overdraft, FX, ATM and maintenance fees, flags stacked overdrafts and drafts a refund request.
Demo:python3 toolbox.py demo fee_detector - Contract Red-Flag Scanner: Scans a contract for auto-renewals, cancellation traps, data sharing and forced arbitration.
Demo:python3 toolbox.py demo contract_redflags - Shrinkflation Detector: Catches shrinking packs that hide a real price rise by comparing price per unit over time.
Demo:python3 toolbox.py demo shrinkflation - Warranty Tracker: Tracks warranties before they expire unnoticed and flags purchases with missing receipts.
Demo:python3 toolbox.py demo warranty_tracker
- Scam Message Checker: Checks a message for phishing, fake parcel and 'Hi Mum' scams, including look-alike links.
Demo:python3 toolbox.py demo scam_check - Fake Shop Checker: Spots fake online shops: irreversible payment methods, 80%-off 'closing down' scripts and an optional domain-age lookup.
Demo:python3 toolbox.py demo fake_shop_check - Rental Scam Checker: Flags fake rental listings: pay before viewing, absent landlord, rent far below market.
Demo:python3 toolbox.py demo rental_scam_check - Voice-Clone Safe-Word Kit: Sets up a family safe phrase and call-back rule against AI voice-clone 'emergency' calls.
Demo:python3 toolbox.py demo voice_clone_safeword - Fake Job Interview Lure Checker: Detects fake-recruiter lures: 'run our repo' tests, ClickFix terminal commands, fake meeting links and moves to Telegram.
Demo:python3 toolbox.py demo job_lure_check - Interview Code-Test Triage: Scans a take-home coding test without running it, for install hooks, VS Code auto-run tasks, credential theft and hidden payloads.
Demo:python3 toolbox.py demo code_test_triage
- GDPR / CCPA Deletion Request Generator: Writes GDPR / CCPA deletion letters to data brokers and tracks their legal deadlines.
Demo:python3 toolbox.py demo privacy_requests
- Heat Risk Planner: Uses the NWS heat index and a live forecast to plan safe hours for outdoor work.
Demo:python3 toolbox.py demo heat_risk - Hidden Water Leak Detector: Finds hidden leaks from continuous night-time meter flow and estimates the yearly waste.
Demo:python3 toolbox.py demo water_leak - Energy Upgrade Payback: Gives an honest payback, NPV and IRR for solar, heat pumps and insulation.
Demo:python3 toolbox.py demo energy_payback
- Caregiver Medication Planner: Helps carers plan medication: run-out dates, a reorder list and a daily dose schedule.
Demo:python3 toolbox.py demo med_refills - Unclaimed Benefits Screener: Screens US and UK benefits worth checking and points to the official calculators.
Demo:python3 toolbox.py demo benefit_finder
- Digital Legacy Planner: Finds digital inheritance gaps (crypto, 2FA, heirs) and writes instructions for your executor.
Demo:python3 toolbox.py demo legacy_planner - Account Recovery Audit: Maps how your accounts recover each other: SIM-swap blast radius, email chains and missing backup codes.
Demo:python3 toolbox.py demo account_recovery_audit - 3-2-1 Backup Auditor: Audits your backups against the 3-2-1 rule and catches 'cloud sync is not a backup' and untested restores.
Demo:python3 toolbox.py demo backup_check - Bit-Rot Guard: Detects silent file corruption using SHA-256 fingerprints.
Demo:python3 toolbox.py demo bitrot_guard - File Format Rescue: Finds files stuck in dying formats and gives the exact command to convert each one.
Demo:python3 toolbox.py demo file_rescue
10 agent skills in juw12/skills: plain SKILL.md files for Claude Code, OpenCode, Codex and SkillMouse
Agents that verify instead of claiming: they run the checks, report honestly and stop when they should. See the README; install with git clone https://github.com/juw12/skills.
- refine-loop: Improve-until-done without babysitting: frozen rubric, baseline score, separate judge, keep-best, blind A/B check against score inflation and hard stop rules. Ships an objective self-checker.
- harness: Finds and actually runs a project's build, test and lint commands, and reports pass/fail truthfully.
- heartbeat: A short, honest status of running jobs and services (servers, watchdogs, long tasks) that flags stalls.
- delegator: Breaks a goal into small tasks, routes each to the best agent or skill, then combines the results.
- soul: Reviews drafts, docs and UI copy against a project's voice and principles, with minimal fixes.
- memory-management: Durable project memory (decisions, lessons, context) in an Obsidian vault, so it survives across sessions.
- widgettheme: Applies "The Morning Paper" editorial design system: cream paper, ink black, newspaper red, serif headlines.
- beacon-push: Send and inspect push notifications through Beacon: Web Push, FCM, ntfy, Bark, Gotify and Apprise.
- tether-android-qa: Drive a real Android phone or emulator through Tether: read the screen, tap, type, swipe and read logcat.
- push-qa-e2e: End-to-end check: subscribe the phone, send a push, assert it shows in the shade, tap it and verify the app opens.
![]() Cozy Island: A cozy 3D island for laptop workers: fish, garden, take tea-breathing breaks and rest your eyes, with Mochi the cat. Play · Landing page · README |
![]() VALE: A first-person explorer: collect five Lumenshards to restore a fading fairy realm. Play · Landing page · README |
![]() Game Library: A searchable collection of browser games by category, with a Surprise Me button. Runs offline in the browser. Play · Landing page · README |
![]() Townsquare 3D: A shared 3D town for phone and desktop browsers: claim land, run crops and workshops, trade at a market that follows supply and demand. Play · Landing page · README |
![]() Hearthwood: A third-person action-adventure prototype with dialogue, quests, inventory and NPC AI. Landing page · README |
Prompt packs and product experiments kept on record
- Handoff
: AI automation agency plus SaaS product for SMBs. Five Next.js apps, cold-outreach copy and a 14-day validation playbook.
Landing page · README - 150 ChatGPT Prompts for Etsy Sellers: 150 copy-paste prompts across 9 sections, packaged as a 6-phase workflow that writes an Etsy listing in 5 minutes. PDF + Notion template.
Landing page · README
The full monorepo: juw12/projects · All repositories · Landing pages
Every public project is released under the MIT License; contributions follow the Contributor Covenant, the contributing guide and security policy.
Independent personal projects. No employer endorsement implied. Demos and prototypes vary in maturity; check each README before use.
If something here is useful, a star on the repo helps, and following @juw12 keeps you posted on what ships next.



















