Isochrone endpoint

Compute a travel-time area from a coordinate. Answers “everywhere you can reach within N minutes” by driving, walking, cycling, or transit.

Request

Response

The body is a bare GeoJSON geometry, not a Feature and not a FeatureCollection. There is no features array to index into.

• Driving, Walking and Bicycling return a Polygon.
• Transit returns a MultiPolygon, because the area reachable by public transport is normally made of disconnected pieces around the stops you can get to. A 15 minute transit area from the Grand-Place in Brussels returned 29 pieces on 21 September 2026, 12 of them with a near-zero area.

Handle both types. Code that assumes a Polygon will break on the first transit call. Set aside the zero-area pieces before drawing or testing containment.

The shape of the response, not an executable response:

{
  "type": "Polygon",
  "coordinates": [
    [ [lon, lat], [lon, lat], [lon, lat], [lon, lat] ]
  ]
}

Each ring is a list of [longitude, latitude] positions, in that order, whose first and last positions are identical: at least four positions per ring, as RFC 7946 requires. Complete, valid responses for the Grand-Place example: walking, Polygon and public transport, MultiPolygon.

Examples

curl -H 'LicenseKey: YOUR_KEY' \
  'https://be.yatmo.com/isochrone?travelMode=Walking&latitude=50.846714&longitude=4.352514&numberOfSeconds=900'

const url = 'https://be.yatmo.com/isochrone'
  + '?travelMode=Walking&latitude=50.846714&longitude=4.352514&numberOfSeconds=900';

const res = await fetch(url, { headers: { LicenseKey: 'YOUR_KEY' } });
const geometry = await res.json();

// Polygon and MultiPolygon nest their rings differently, so normalise once
// and the rest of your code stops caring which mode was requested.
const polygons = geometry.type === 'MultiPolygon'
  ? geometry.coordinates
  : [geometry.coordinates];

const ringCount = polygons.length;
const outerRing = polygons[0][0];          // [[lon, lat], [lon, lat], ...]

// Ready to hand to MapLibre, Leaflet or turf as a GeoJSON geometry:
map.getSource('reachable').setData(geometry);

$qs = http_build_query([
    'travelMode' => 'Walking',
    'latitude' => 50.846714,
    'longitude' => 4.352514,
    'numberOfSeconds' => 900,
]);
$ch = curl_init("https://be.yatmo.com/isochrone?$qs");
curl_setopt($ch, CURLOPT_HTTPHEADER, ['LicenseKey: YOUR_KEY']);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$geometry = json_decode(curl_exec($ch), true);
curl_close($ch);

$polygons = $geometry['type'] === 'MultiPolygon'
    ? $geometry['coordinates']
    : [$geometry['coordinates']];

using var http = new HttpClient();
http.DefaultRequestHeaders.Add("LicenseKey", "YOUR_KEY");

var qs = "travelMode=Walking&latitude=50.846714&longitude=4.352514&numberOfSeconds=900";
var json = await http.GetStringAsync($"https://be.yatmo.com/isochrone?{qs}");

using var doc = JsonDocument.Parse(json);
var type = doc.RootElement.GetProperty("type").GetString();  // Polygon or MultiPolygon

Variants

• GET /isochrone: the standard endpoint above. Returns one geometry.
• GET /isochrone/TravelTime: same parameters, same response shape, a faster computation path for driving, walking and cycling. Verified byte-identical to /isochrone for a walking request.
• GET /isochrone/GetMultipleTimes: returns the 5, 10 and 20 minute areas in one call. It takes language instead of numberOfSeconds, and its response is a JSON array, not a geometry.

GET /isochrone/GetMultipleTimes?travelMode=Walking&latitude=50.846714&longitude=4.352514&language=EN

[
  { "label": "5 min",  "iso": { "type": "Polygon", "coordinates": [ ... ] } },
  { "label": "10 min", "iso": { "type": "Polygon", "coordinates": [ ... ] } },
  { "label": "20 min", "iso": { "type": "Polygon", "coordinates": [ ... ] } }
]

The label is already localised for the language you asked for, so it can be shown as is. Each iso follows the same rules as the single geometry above.

Notes

• The area is computed outwards from the origin. It answers “where can I get to from here”. It does not answer “who can get to here”, which is a different computation: travel times are not symmetric, because one-way streets, timetables and turn restrictions are not.
• Do not request huge time horizons. 30 and 60 minute areas take many seconds to compute and produce very large geometries. Stay with 5, 10 and 20 minutes unless you really need more.
• Transit availability varies by country. Transit needs GTFS data; some countries have full coverage, others only their major cities.

See a travel-time area on a property page