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Austin, Texas · 30.29° N · July, 3:00 PM

Walk-Free

See how hot every street feels at the hour you walk it, then take the shady way there.

Heat-aware walking for campuses and cities, built for the Meta Global AI Developer Hackathon (Indie track). Meta’s Muse Spark plans the walk in your own language; the map works without an account.

Try the demo (opens the UT Austin tour in a new tab)Visit the site (opens in a new tab)Code on GitHub (opens in a new tab)
Walk-Free at UT Austin: a 3D campus with green tree crowns, a blue and orange shade route from Start to Finish past the UT Tower, and route cards reading Quickest 14 min and More shade 15 min with 55% less sun.
The real app at UT Austin. The more-shade walk is 15 minutes against 14 for the quickest, with 55% less sun.

Walk-Free in numbers

  • 6

    campuses ready to open: UT Austin, UC Berkeley, Michigan, UCLA, Stanford and Arizona State

  • 10,000+

    buildings, each casting a modelled shadow for the hour you pick

  • 900+ km

    of walking paths, coloured from full shade to full sun

  • 6

    route types: quickest, more shade, scenic, cool stops, step-free, lit at night

Below is a small district drawn for this page, run through the same steps as the app: sun position for a July day in Austin, building and tree shadows projected from it, and every path sampled as shaded or in sun. Scroll to move the clock.

Same street, every hour.

Afternoon, the hottest stretch. Shade survives under Cedar Lane's trees and in thin strips beside tall buildings.

An illustrative district at 3:00 PM in JulyBuilding and tree shadows for the sun at 69 degrees from the WSW. 43 percent of the paths are shaded. Solid blue paths are in shade, dashed paths are in direct sun.

In shade In direct sunSun 69° up, from the WSW

Trade a minute for the shade.

Across the six campuses on a July afternoon, shade routes avoid 13–25% of the sun for 4–7% more walking. The sun-aversion slider (1 to 6, default 3) sets how many metres of shade one metre of sun is worth.

Two walks across the illustrative district at 3 PMThe quickest walk takes 18 minutes with 11% of it in shade. With sun aversion 3, the shade route takes 19 minutes with 81% in shade.

From A (Quarry Road) to B (Lantern Row) at 3 PM. The highlighted walk is drawn in full; the other is dotted.

At 3, a metre in the sun counts as 3 metres in shade. The route leaves the avenue for tree-lined Bluff Walk and Cedar Lane.

Quickest

18 min

Distance
1.41 km
In shade
11%
In sun
16 min
Feels like
~116 °F

More shade (highlighted)

19 min

Distance
1.48 km
In shade
81%
In sun
4 min
Feels like
~108 °F

78% less sun

78% less sun for 5% more walking.

Six kinds of walk

  • Quickest

    The shortest walk, whatever the sun.

  • More shade

    Weighted by the sun-aversion slider.

  • Scenic

  • Cool stops

    Through air-conditioned libraries and unions.

  • Step-free

    Never takes mapped stairs or slopes over 8%.

  • Lit at night

    Keeps to lit streets after dark.

Plant a row, watch it cool.

The design studio lines a street with trees and shows shade share and feels-like before and after, for the street and the whole area. One button writes it up as a one-page proposal; another downloads the street heat as CSV for planners.

Long Avenue at 3 PM as it isLong Avenue is 13 percent shaded and feels like about 116 degrees Fahrenheit on average.
Pick a hot street
Shade on Long Avenue13%
Feels like on Long Avenue
116°F
Shade across the district42.7%

Trees no one mapped.

Volunteers map street trees, not back gardens or creek banks. Walk-Free reads Meta and WRI’s 1 m Canopy Height Maps (v2, built with DINOv3) on the server, by byte range from cloud-optimised GeoTIFFs. A 9 m cell becomes a crown when at least 45% of it stands 3 m or taller.

At UC Berkeley that turns about 216 mapped trees into roughly 11,100. Drag the divider to compare.

Tree cover across an illustrative district. Left of the divider: only trees mapped in OpenStreetMap. Right of the divider: mapped trees plus crowns inferred from Meta and WRI canopy-height maps. One dot stands for about 75 trees.

4,375trees mapped in OpenStreetMap across the six campuses

+33,136inferred crowns in view (of 62,748), from the canopy-height maps

Measured, then walked.

Every number in the app comes from open data, recomputed for the hour you choose. Feels-like is labelled as an estimate, not a measurement. If one weather source is down, the next one answers; if the walking graph has a gap, quick walks fall back to OSRM, then Valhalla, then a labelled straight-line estimate.

Ask Walk-Free (an illustrative exchange; the tool names are the app’s own)

Shadiest way from the library to the union at 3?

  1. find_places
  2. plan_route
  3. best_time_to_leave
  4. compare_walks

The shade route on the map takes a minute longer and keeps you out of the sun for most of it. Leaving at 5 would feel cooler still.

Itinerary for one walk

The ground

Streets, paths, buildings, trees from OpenStreetMap
Overpass
Tree crowns from 1 m canopy-height maps
Meta + WRI

The sky

Temperature, humidity, sunlight in W/m², UV
Open-Meteo
Heat and air-quality alerts, HeatRisk
NWS
Air quality (US AQI)
CAMS

The walk

Sun position for the chosen hour
any hour
Shade ray-traced against buildings and crowns
per path
Feels-like: heat index, plus up to 8 °C in sun
estimate
Shade-weighted shortest path
6 types

Result: the walk, coloured by heat, with minutes in sun

Seven invented cities, seven weathers.

Describe any city and the assistant plans districts, sixteen kinds of landmark, street names, climate and sky. A deterministic builder makes it walkable in under 200 ms, with walkers who thin out at night and drift toward shade in the heat.

  • Noir Harbor

    Fictional cityRain, 9 PM

    Black towers, gold windows and rain that never lets up.

  • Skyline Prime

    Fictional cityClear, glare

    Chrome towers and wide boulevards in hard noon light.

  • Velocity Bay

    Fictional cityBay breeze

    Long straight avenues off the bay, where the wind leaves streaks.

  • Aurora Realm

    Fictional cityAurora

    A golden citadel at the edge of the northern sky.

  • Neon District

    Fictional cityNight, neon

    The night never ends under a thousand signs.

  • Dune Reach

    Fictional cityDesert, 3 PM

    The open boulevards bake; the old quarter's lanes keep the shade.

    Quickest route 0% shade. Shade route 68%.

  • Verdant Canopy

    Fictional cityUnder canopy

    A city that grew a forest over every street.

    87% of walking in shade.

  • Or describe your own.

    “a rain-soaked noir city from a 90s cartoon”

    The assistant plans districts, landmarks, street names, climate and sky; a deterministic builder turns that plan into a walkable city.

    GeneratedRavenmoor

    930 buildings, built in 0.2 s

From the real app.

  • Landing page section titled Same street, different hour: a UT Austin map with paths coloured from blue shade to red sun, a 116 °F feels-like readout and a time-of-day slider.
    Heat on the groundUT AustinPaths coloured by feels-like at the chosen hour
  • Noir Harbor, a fictional city at 9 PM: black towers with lit gold windows, falling rain and a zig-zag walking route.
    A generated cityNoir HarborRain layer at 9 PM
  • Walk-Free landing page: a dark green hero with the headline The cooler way across campus is already there, over a glowing blue campus path network and a 117 °F callout.
    The first screenLandingHemphill Park, 117 °F in full sun at 3 PM in July
  • Walk-Free on a phone: the map on top and a bottom sheet with route options below.
    Bottom-sheet layoutPhoneInstallable PWA, works offline

What it’s made of

  • React 19
  • TypeScript
  • Vite
  • three.js / React Three Fiber
  • MapLibre
  • Express 5 on Vercel
  • Neon Postgres + Neon Auth
  • Capacitor
  • Meta Muse Spark

Four interface styles: Editorial, Night, Sunlight (high contrast for glare) and Blueprint, in °F or °C. The walking view follows you on a flat north-up map with next-turn banners like “In shade for 120 m”, and can speak the guidance.

Installable as an offline PWA, with Capacitor projects for iOS and Android (not yet tested on devices). About sixty test files cover the model, routing and tools.

Take the shady side.

The guided demo opens UT Austin and walks through a shade route in about a minute. No account needed.

Try the demo (opens in a new tab)Read the code (opens GitHub in a new tab)