香港體感
See how hard Hong Kong feels today — eighteen-district heat, AQHI, widgets.
STATUS LIVE · iOS · APP STORE
Open App Store ↳RAINSDAY — EDITION 05
Build for what's next.
A Hong Kong studio for iOS, web, automation and brand systems. This year, we built a black hole. Scroll to fall in.
01 — THE APPROACH
We are rainsday.
Small studio, heavy pull. We take rough ideas and compress them until they shine — iOS apps, web tools, automation, brand systems. Polished until they feel inevitable.
設計から実装、運用まで、一貫して。
02 — IN ORBIT
Work in stable orbit.
Six missions in orbit. Five live, one inbound.
WildFrog 野青蛙
GPS summit check-ins for Hong Kong's 330 peaks — collectible certificates, equippable titles, live trail tracking.
STATUS IN REVIEW · iOS · 330 PEAKS
Ask about it ↳
expenseCal
Travel expenses and friend splits — multi-currency, net settlement, now live.
STATUS LIVE · iOS · MULTI-CURRENCY
Open App Store ↳
RaIN JLPT Grammar Lab
310 grammar drills with memory, N3/N2, weak-point practice.
STATUS LIVE · WEB · 310 DRILLS
Open lab ↳
Research & longform
CSV, chat-log and Excel analysis with a designer's output. Reports that ship.
ON REQUEST · DOCS
Ask about it ↳03 — TIME DILATION
Near the horizon, time runs slow.
That's where we work. Deep in the gravity well of a problem — small habits, shipping discipline, craft that compounds. One hour here is a launch out there.
- 01 — SHIP FIRST. POLISH EVERY ORBIT AFTER.
- 02 — AI IS THE STAFF. DIRECTION IS MINE.
- 03 — EVIDENCE BEATS PLANS.
- 04 — MATCH THE REFERENCE. APPROXIMATION ISN'T DESIGN.
×1.31 AND CLIMBING
04 — EVENT HORIZON
Transmission log.
- 2026.06.12 — LAB 01: a real-time black hole with true gravitational lensing
- 2026.06.12 — expenseCal: eight cloud functions live; 195 web + 122 rules tests green
- 2026.06.11 — WildFrog 1.0 submitted to App Store review
- 2026.06.10 — expenseCal iOS functional audit: submit-ready
- 2026.06.09 — WildFrog: 330 collectible peak titles, honest GPS check-in
- 2026.06.06 — 香港體感: feels-like formula rebuilt on apparent temperature
- 2026.06.06 — codex-pet-meter v0.3.0 open-sourced on GitHub
- 2026.06.04 — 香港體感 1.0 live on the App Store
- 2026.05.27 — edition 04 archived
- 2026.05.26 — expenseCal 1.5: net settlement and pair batches GA
- 2026.05.22 — vibe code: three Claude Code skills shipped
⚠ 1.5 rs TO PHOTON SPHERE
05 — ESCAPE VELOCITY
Let's build what's next.
New commissions, partnerships, advisory. Send a brief — we reply within one business day.
hello@rainsday.com