# Routing algorithm of open route service

**URL:** <https://ask.openrouteservice.org/t/routing-algorithm-of-open-route-service/2249>\
**Category:** isochrones\
**Created:** [October 29, 2020, 11:17am UTC](https://ask.openrouteservice.org/t/routing-algorithm-of-open-route-service/2249 "2020-10-29T11:17:41Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Elham](https://ask.openrouteservice.org/letter_avatar_proxy/v4/letter/e/bbce88/32.png) [@Elham](https://ask.openrouteservice.org/u/Elham)\
**Post date:** [October 29, 2020, 11:17am UTC](https://ask.openrouteservice.org/t/routing-algorithm-of-open-route-service/2249/1 "2020-10-29T11:17:41Z")

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what is the routing algorithm that open route service uses to generate isochrones?

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**Author:** ![Elham](https://ask.openrouteservice.org/letter_avatar_proxy/v4/letter/e/bbce88/32.png) [@Elham](https://ask.openrouteservice.org/u/Elham)\
**Post date:** [October 30, 2020, 5:20pm UTC](https://ask.openrouteservice.org/t/routing-algorithm-of-open-route-service/2249/2 "2020-10-30T17:20:39Z")

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According to Futterer (2017), OpenRouteService uses A\* algorithm

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**Author:** ![nils](https://ask.openrouteservice.org/user_avatar/ask.openrouteservice.org/nils/32/6_2.png) [@nils](https://ask.openrouteservice.org/u/nils)\
**Post date:** [October 31, 2020, 5:44am UTC](https://ask.openrouteservice.org/t/routing-algorithm-of-open-route-service/2249/3 "2020-10-31T05:44:37Z")

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No, not for isochrones… a modified A\* is used for some of the flexible routing stuff (I think), isochrones should be mostly plain dijkstra, with some fancy preprocessing for the fast isochrones.