Route360 has released an API to provide developer access to their isochrone library. The API has been designed to provide simple access to the Route360 isochrone travel time library from the Leaflet.js mapping platform.
You can see the Route360 isochrone library in action on SONA's map of apartments to rent in Berlin by travel time.
This apartment search map allows you to search for available apartments within a defined travel time of your workplace or other location. All the areas you can travel to on public transit in your
commute time are shown on the map with an isochrone layer.
The isochrone layer is colored in ten minute segments, so you can easily
tell at a glance how long it would take to travel to each of the
displayed properties. If you select an apartment's marker on the map you
can view all the details about the apartment. A transit route is also
automatically displayed on the map showing your route from work to the
apartment and how long the journey would take.
The Nokia Here Map API also includes a calculate isoline option. Nokia provide a neat demo map which uses the resulting
isochrone polygon from a calculate isoline travel time search as the bounding box for a
places search. The Isoline Bounding Box Search
map is a nice demonstration of how you could use Nokia's isoline
calculator to refine searches on a map, for example you could create a
map that allowed users to search for cafes within a ten minute walk of
their current location.
You can see the Nokia calculate isoline function in use at Isoscope. Isocope
provides a beautiful mapped visualization of how far you can travel by
car in a chosen time from any location in the world. You can even select
the day and time to view an isochrone view of your time restricted
If you prefer to use the Google Maps API then you can use the Mapnificent API to add isochrone layers to you maps. The API only works where Mapnificent has transit time coverage but this includes major cities in the US and other world-wide cities (you can check out the current coverage of the API on the Mapnificent coverage map).