the engineering story

Twenty extra minutes. Make them count.

astray is for people who sometimes care about the drive as much as the arrival. Give it a destination and the extra minutes you can spare, and it finds roads worth spending them on. This page is the whole story in a few minutes; every section links to a deeper dive.

why it exists

It started in traffic.

astray began on a jammed stretch of Highway 101, watching the ETA climb. Bailing onto Sonoma backroads that day cost five extra minutes against the traffic estimate, and it was the best hour of driving all month. The product is that moment made repeatable: get a little lost, without losing control of the trip.

Most navigation apps are built around one goal: arrive quickly. Their controls stop at avoiding highways or tolls, and cannot express a different request: "I have twenty extra minutes. Spend them on roads worth driving." That one sentence is the whole product, and honoring it took more engineering than we expected.

what it does

You bring the time. It finds the roads.

You pick a destination and the most extra time you are willing to spend. astray plans a route that treats your limit as firm and spends the allowance where the map offers something worth the minutes: a forest road here, a ridge with a view there. A detour has to earn the time it costs; an unavoidable dull bridge just gets crossed at full speed. When you are happy with the route, astray hands it to the navigation app you already use. And if home is also the destination, it plans a loop: out on one road, back on a different one.

It also listens to taste. Water, forests, sweeping bends, empty roads, or gentle roads only if switchbacks make someone in the back seat queasy. Those preferences are called moods, and you can tune one like an equalizer: more coast or forest, fewer signals, windier bends, higher vistas, nothing you have driven recently.

how it works

The whole trick, in three sentences.

First, we do the homework ahead of time. We read the free, public map of the world and give every stretch of road a report card of fourteen small measurements, such as how bendy it is, how steep, how close to water, and how far from anything industrial.

Then, at request time, we go shopping. The engine turns your mood into a price it is willing to pay for scenery and searches for the best drive your spare minutes can buy without exceeding the time you offered.

And it is nobody's business where you drive. The same engine that runs on our server also runs entirely on your own device, and the server tier keeps no logs and no accounts either way.

who makes it

A small shop, on purpose.

astray is a Formentia project. We keep the longer introduction, and the other things we have built, over there.

the wiki

Dig as deep as you like.

Each article below opens in plain language and works its way down to the algorithms and the measured numbers. Read one, read them all, or come back when you are curious.

the routing engine · 8 min How a time budget becomes a route. You give it spare minutes; it shops for the best drive those minutes can buy. How a router learns to spend time instead of only saving it. read the deep dive → the loop problem · 7 min The loop problem: ending where you started. The request "take me out for an hour and bring me home" has no destination. Why that quietly breaks a router, and how we taught ours to circle back. read the deep dive → the scenery model · 7 min What counts as scenic, and who decides. "Scenic" is not one thing. The fourteen things we measure about every road, and why bendiness is not sharpness and a city park is not the countryside. read the deep dive → moods and the equalizer · 6 min Tuning the drive: how custom moods work. A mood like Back roads or Gentle is just a set of numbers you can edit. How an equalizer for taste becomes arithmetic the router can act on. read the deep dive → the bake · 7 min Teaching a computer what a road feels like. Before any route is planned, we read the public map of a whole region and give every road a report card. What is in it, and how it gets made. read the deep dive → architecture and privacy · 8 min Private by architecture, not by promise. Where you drive is nobody's business, so the whole engine can run on your own device. What building for that first did to everything else. read the deep dive →

quick answers

Simpler questions have a simpler page.

Does it need internet? What data do we collect? Why is the route different from Google's? Those live in the FAQ. The build report publishes the health of the live map data: sizes, freshness, and whether the API matches the tile mirror.

The best way to evaluate a router is to drive it.

There is no account and no tracking. Open it, pick somewhere you've been meaning to go, and give it twenty spare minutes.

open the app → back to astray.to FAQ Build report Terms Privacy