YUBI — Point. Show. Connect.

An offline emergency communication app. When you can't speak, don't share a language, or have no connection — point at one card, and help gets through.

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Demo video: Watch on YouTube

Inspiration

Imagine an earthquake hits Tokyo. A tourist is injured in a subway station. She can't speak Japanese. She has lost her voice from shock. The network is down. How does she ask for help?

Japan expects a major earthquake within decades, and hosts millions of visitors who don't speak Japanese. In a real emergency, three things fail at once: your voice, your language, and your connection. I built YUBI (Japanese for "finger") because in that moment, pointing at a screen should be enough.

What it does

YUBI is a single-page emergency communication app:

  • Choose what's happening from urgency-ordered picture cards (injury, illness, fire, trapped, etc.)
  • Show the screen — your message appears in large, high-contrast text in the responder's language (English, Japanese, Chinese, Korean, Spanish)
  • Tap to speak — the phone reads the message aloud via text-to-speech, so it works even if the responder can't stop to read
  • Works offline — once loaded, YUBI runs entirely on the device. My demo video shows it working in airplane mode
  • Zero barriers — no account, no installation, no data leaves the device

I also designed a future concept, YUBI Station: a dedicated kiosk device for evacuation shelters that serves YUBI over local Wi-Fi to people who never had a chance to prepare. It is clearly labeled as a concept on the site — I show what works today, and stay honest about what doesn't work yet.

How I built it

Built at Global Build Week Tokyo (an official Build Week community hackathon) in a 3-hour build window, entirely with Codex powered by GPT-5.6 (Sol) in VS Code. Not a single line of code was written by hand — I directed Codex in Japanese, and Codex wrote, fixed, and deployed everything. I'm a solo builder, and not an engineer.

My workflow, refined through pre-event practice runs:

  1. Deploy-first strategy: in the first 20 minutes, Codex initialized git, created the public GitHub repo via gh, and deployed a placeholder to Cloudflare Pages via wrangler — so a live demo URL existed before the product did
  2. One-word deployment loop: throughout the build, saying "deploy" made Codex commit → push → redeploy, keeping the live URL always current
  3. AGENTS.md as guardrails: my project instructions banned fake UI (any control not wired to logic must be labeled "not implemented"), banned invented facts, and enforced a feature freeze 30 minutes before the submission deadline

The app itself is a single static HTML/CSS/JS file — no framework, no backend — which is exactly why it can run offline and load instantly on any phone.

Challenges I ran into

  • The 3-hour limit: I cut everything that wasn't the one demo path (no accounts, no database) and spent the saved time making the core path bulletproof
  • Non-engineer, solo: I first touched Codex only days before the event. The answer was preparation: rehearsing the deploy pipeline twice on practice projects, and encoding my lessons into files Codex reads
  • Honesty under time pressure: it's tempting to demo features that don't exist. I chose to ship the YUBI Station idea as a clearly-labeled concept page instead of faking it

Accomplishments that I'm proud of

  • A working, offline-capable, five-language emergency tool — live on the public internet — built in 3 hours by a solo non-engineer who wrote zero lines of code
  • The demo video shows the phone in airplane mode: the offline claim is real, not a slide
  • Honest scope labeling ("concept", "not implemented") as a design principle, not an afterthought

What I learned

Codex with GPT-5.6 removes the coding barrier — so the differentiators become problem selection, scope discipline, and verification. A non-engineer who knows the problem deeply, directs the agent clearly, and refuses to fake what doesn't work can ship something real in an afternoon.

What's next for YUBI

  • More languages and symbol-first cards for children and low-literacy users
  • Proper PWA packaging (installable, guaranteed offline via service worker)
  • YUBI Station prototype: a shelter kiosk serving YUBI over local Wi-Fi, no internet required
  • Field feedback from disaster-preparedness communities in Japan

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