Heading out
What you wear and pack at the door
- Blue Oxford Shirt
- Grey Wool Trousers
- Brown Leather Shoes
- Merino Socks
01 · Personal product
WhatToWear.
A phone app that turns the weather, your own clothes and where you're going into one honest outfit answer.
- Product, design and code
- Mar 2026 – now
- Pre-launch, in development
One day in Chicago
Drag the sun across the sky, or focus it and use the arrow keys.
Morning
Wear now · Feels like 64°F
Warm cream in the morning. The same plan, in the app's own colours for that part of the day.
Morning· The answer
One answer first, from your own clothes.
Today opens on one conclusion, here “No jacket needed”, with the felt temperature and the next change under it. The reasons are one tap away, not in the way.
The plan is chosen only from the clothes you have listed, never from a catalogue. The solver tries sets of them against structure, layering and weather checks; each check passes, fails or stays unknown, and it looks at no more than 8,192 sets for one answer.
Conclusion firstYour wardrobe only8,192 sets at most
Heading out· The commute
Your commute, stage by stage.
A usual commute proposes the day's window. Once you confirm it, the plan is what you wear and pack at the door, checked against each stage's own hourly forecast; sheltered stages check only that the outfit holds together, and nothing is re-chosen after you leave.
Up to 6 stages · stages with zero minutes are skipped
Walking
12 minChecked against this stage's hourly forecast
Waiting
6 minChecked against this stage's hourly forecast
On board
20 minSheltered: checks only that the outfit holds together
Indoors
0 minZero minutes: skipped
Return
Checked against this stage's hourly forecast
A rough area, never your spot.
A precise location is used only for the weather request and a short cache. What is kept is an area rounded to a tenth of a degree, about 11 km north to south, and saved places, up to 12, are matched by that area.
Noon· Feels like
Felt temperature, by the NWS formulas.
When the forecast's own apparent temperature is missing, the app works it out with the National Weather Service formulas: wind chill at 50 °F and below with wind over 3 mph, the heat index from 80 °F, and the air temperature in between.
In the app this is the fallback: Open-Meteo's apparent temperature is used when it is there.
41 unit tests
Feels like
NWS formulas, as in feltTemperature.tsAir temperature
64 °F18 °C
- Wind chill: 50 °F or below, wind over 3 mph
- Heat index: 80 °F or above
- Air temperature: anything in between
2 PM· Rain likely
Rain at 2 PM, and nothing waterproof confirmed.
Rain needs a waterproof layer and none is confirmed, so the plan is held back as Limited guidance and the gap is named.
It asks whether that rain jacket is waterproof: Yes, No or Not sure. Only your answer counts as evidence; a catalogue tag, a name or a photo never does.
Waterproof layer needed
Is your Rain jacket waterproof?
Only if sure · This item only
- Structure: top, bottom, shoes, socksPasses
- Layering: nothing clashesPasses
- Weather: a confirmed waterproof layerUnknown
Limited guidance
Nothing waterproof confirmed
Candidates
- Blue Oxford Shirt
- Grey Wool Trousers
- Brown Leather Shoes
- Merino Socks
6 items · 64 sets, under the 8,192 limit. A simplified version of the app's checks, with its test wardrobe.
Every plan carries “No safety guarantee”. The comfort ranking is a preference rule, not a measurement of warmth.
Scroll inside the phone
Evening· A warning
An official warning comes before the outfit.
A National Weather Service warning sits above the outfit, with its instructions one tap away, and holds the plan back: follow official instructions first; a clothing plan does not make travel safe.
Open-Meteo is the one forecast source, checked against the NWS forecast grid; where they disagree, the plan states the limit instead of quietly switching. A failed alert check never counts as no alerts.
Alerts rechecked within 5 min
The app’s screen under a warning · scroll inside
Limits on the card
No limits on the card
The plan
Chicago · Now only
Wear now
Feels like 64°F
Wear
Blue shirt · Shoes · Socks · Trousers
Clothing checks met for now.
After the trip· One question
Learning you can take back.
After a worn, confirmed trip it asks one question: too cold, just right or too warm. Once there are two answers, the felt temperature the plan uses moves by 2 °C times their average, and deleting an answer rebuilds the result from the rest. Skipping it records nothing.
Comfort now
After a worn, confirmed trip0 answers so far
Too cold −1 · Just right 0 · Too warm +1−1 · 0 · +1
Choose to answer
Learning
— °C
0 of 2 answers: no change yet
2 °C × the average, once there are two answers
- No answers yet
Night· Before a release
A gate before every release.
A release first passes a 12-step local gate: the tests, coverage floors that are never lowered, the production build and the database checks. Its gate result, approval and deployment are recorded apart, and one switch can pause guidance so that every build chooses no clothes and says why.
Release gateStep 1 of 4
npm run quality:gate
- 1Local dev-bindings check and its tests
- 2Lint
- 3Typecheck
- 4Core tests
- 5Extended tests
- 6Preview tests
- 7Core coverage gate
- 8Production build
- 9Core bundle boundary
- 10D1 Worker tests
- 11D1 Worker typecheck
- 12D1 local schema smoke
Gate passed
Recorded apartGate resultApprovalDeployment
In figures
8,192
outfit sets checked at most for one answer
60
fixed Chicago scenarios, all passing
2,812
core tests passed in the 3 Oct 2026 run
12
steps in the release gate
842 commits on main since 18 March 2026. It began as a broad weather dashboard, with a radar map and travel, climate and seasonal modules that are now paused, and has been phone-only since 4 September 2026.
Built with
- Next.js
- React
- TypeScript
- Tailwind CSS
- Cloudflare Workers
- Cloudflare D1
- Open-Meteo
- NWS API
- Vitest
- Playwright